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Moorestown Free Library

Moorestown, New Jersey

Danny Dunn and the Fossil Cave

Also by Jay Williams and Raymond Abrashkin

DANNY DUNN AND THEANTI-GRAVITY PAINT

DANNY DUNN ON A DESERT ISLAND

DANNY DUNN AND THEHOMEWORK MACHINE

DANNY DUNN AND THEWEATHER MACHINE

DANNY DUNN ON THE OCEAN FLOOR

DANNY DUNN AND THE HEAT RAY

DANNY DUNN, TIME TRAVELER

DANNY DUNNand the

FOSSIL CAVE

by Jay Williams &: Raymond Abrashkin

Illustrated by Brinton Turkic

McGRAW-HILL BOOK COMPANYNEW YORK TORONTO LONDON

This book is for Sally Hyman

and for Lance Richard King

T

Acknowledgments

The authors wish to express their thanks to John Atwood—Director

of Research, Perkin-Elmer Corporation—for technical advice andinformation, and to Rose Wyler of Science Materials Center, for

information concerning the Geiger-Miiller Counter.

DANNY DUNN AND THE FOSSIL CAVE

Copyright © ig6i by Jay Williams and the estate of RaymondAbrashkin. Printed in the United States of America. All rights re-

served. This book or parts thereof may not be reproduced in any

form without written permission of the publishers.

Fifth Printing

Library of Congress Catalog Card Number: 61-13173

Contents

1.

Digitized by tine Internet Arciiive

in 2010

littp://www.arcliive.org/details/dannydunnfossilcOOwill

CHAPTER ONE

From a Clear Sky

Danny Dunn, his face flaming almost as red as his

hair from the August heat, came panting up on

the summit of the Sugarloaf, the highest point

of the hills above the town of Midston. Hepaused, mopping his forehead, and looked out

over the wide valley below, at the little toy blocks

of houses, the red brick of the College buildings,

and beyond them, the shining silver of the res-

ervoir lake.

Then he shouted over his shoulder, "Irene

I

Joe! Come on! It's this way."

Irene Miller and Joe Pearson toiled up behind

him. Joe's long thin face was even gloomier

than usual, and as he came to the flat stones at

the summit he gave a loud, sad sneeze.

"Bless you," said Irene, switching her glossy

dark pony-tail from side to side to drive away the

gnats which buzzed around her face. "Don't tell

me you're catching cold on a hot day like this?"

"Id's nod a code," Joe mumbled. "Id's ad-

dergy."

9

"Addergy? Goodness, Dan, do you think

that's something catching?" Irene grinned.

"Allergy, I guess he means," Danny said.

"Poor old Joe. He's allergic to climbing, to ex-

ercise, to perspiring, to mountains—

"

"Okay, okay," Joe howled, flapping his hands.

"Very fuddy. The side of the hill is all cubbered

wid godded-rod, ad I'b addergic to dat!"

Danny looked sympathetically at his friend's

red nose and streaming eyes. "Well, there's no

goldenrod up here," he said. "And the breeze

ought to make you feel better. Let's rest for a

minute."

They made themselves comfortable on the

sun-warmed stone, and Danny pointed to a bulge

of gray rock swelling out on the mountain face

below them. A wide crack split it diagonally.

"We can follow that crack down," he said.

Joe glanced at his watch. "Eleved o'clock,"

he said.

"I know just what you're thinking," said

Danny. "Do we have time to find the cave, ex-

plore it, and still get home in time for lunch?

Right?"

Joe nodded, and blew his nose several times.

He was beginning to feel a good deal better in

spite of himself, and when he spoke again it was

in a clearer voice. "It isn't that I'm hungry," he

10

said. "It's just that I haven't had anything to eat

since breakfast."

"Not counting those two candy bars and the

apple," said Irene.

"I mean real food."

Dan, with his elbows on his knees, peered out

over the countryside. "Gosh, it's pretty up

here," he said. "Makes you feel like a giant.

Just think, there was a time when all that valley

was water."

"Water? You mean some kind of flood?" said

Joe.

"No, Professor Bullfinch says that all this part

of the country was once covered by a sea. Whatwe're standing on was part of the bottom."

"Good thing it isn't a sea now," Joe remarked.

"We'd have to go to school wearing aqualungs."

"Oh, Joe, that was millions of years ago," said

Irene. "Maybe even before the dinosaurs

lived."

"Then how does Professor Bullfinch knowabout it? He's no dinosaur," said Joe. He lay

back and stared up at the sky, yawning.

"Scientists find out from studying the rocks

and the clay and sand, and types of earth, and

the fossils in them," Danny replied. "And be-

lieve me, what Professor Bullfinch doesn't knowabout science isn't worth knowing."

11

Danny had been brought up in the house of

Professor Euclid Bullfinch, who taught at Mid-

ston College and who was famous for his private

researches. Dan's father had died when the boy

was very young, and Mrs. Dunn had taken the

job of housekeeper for the Professor. Between

the scientist and the child a real affection had

grown up, almost like that of father and son, and

the Professor had taught Dan a great deal about

the wonders of science.

The boy continued, "They've found fossils

of shellfish and plants and things that show howthe sea bottom filled up with mud. Thensomething—maybe earthquakes—changed the

course of the streams and the sea dried up or re-

ceded. Now there are only a few little trickles

left, and Midston River, and the reservoir."

"Gosh, maybe we'll find some fossils in the

cave," murmured Irene.

"Ifweeverreachit,"said Joe. "Come on, let's

get going. The sooner we find it, the sooner we

can go find some sandwiches."

Danny began the descent along the crack in

the rock, setting his feet in it with care and brac-

ing his hands against the face of the stone. After

a short distance, the crack widened until it was

a narrow shelf that ran diagonally along the

12

rocky face. This, in turn, gave way to great

ragged boulders among which grew scrub oaks

and junipers. There were blueberry bushes,

too, weedy grass, and then, a little further down,

the woods began.

Dan led his friends between the dark trunks

of the pines. The ground was slippery with

needles, and there was a spicy smell of resin in

their nostrils. Gray beech trees and the rough

bark of maples appeared, and the going became

harder as the smooth carpet of needles gave way

to underbrush, to partridge berry and sassafras,

and tangles of blackberry vines. A pheasant shot

up like a rocket with a clap of wings that madeall three young people jump. A jay scolded

them noisily as they clattered down the slope

hanging on to saplings to keep from sliding head-

long. The forest thinned. They emerged be-

side a long ridge of rock, partly covered with

moss and shrubs, that stuck out of the ground

like the back of a giant beast.

"It's not far from here," said Danny, with sat-

isfaction.

Joe groaned. "Not far! That's what you've

been saying ever since you talked us into coming

with you this morning. If you had told me I

was going to have to climb up over Sugarloaf— I"

13

"Yes, Dan," said Irene. "Why couldn't we

have come right up this side, nearest the town?

It would have been shorter."

Danny nodded. "I know. But the trouble

is, when I first found the cave, last spring, I didn't

mark the trail to it. I was looking for mineral

specimens for my collection and I took the road

from the end of town up behind Sugarloaf, and

past Rose Hill. Then I climbed Sugarloaf and

started down this side. So I remember the land-

marks from this direction but not the other."

He made his way down the slope until he was

standing in the shadow of the ridge. When his

friends had joined him, he said, "Now, let's see.

I followed the bottom of the ridge and came out

on a kind of point of ground where there was a

big white oak. The cave was just below it ... I

think."

"You think?" Joe said.

"No, I'm sure of it. Stop worrying, Joe."

He strode resolutely on. But suddenly, Irene

caught his sleeve.

"Listen," she said. "What was that?"

They stood still, cocking their heads. "I don't

hear anything," said Danny.

"There it is again. Sh!

"

They all heard it now, a faint, sharp tapping

14

as of metal striking stone. It seemed to come

from the ridge at their backs.

"That's just a woodpecker," Danny said,

shrugging.

"Doesn't sound like a woodpecker to me," said

Joe. "More like a pebble-pecker. Tell you

what—let's go home."

Danny frowned at his friend. "You don't

really mean that, Joe."

"I don't? Oh. I thought I did."

"And anyway, I'm not going to turn back

now," Dan went on. "When I found the cave,

I didn't have any light with me, not even a

match. I planned to come back next day, but

the next day was a school day and I forgot.

Then, next time I remembered about it there

was a baseball game I had to play in. Something

always interfered—that camping trip one week

end, and then Irene's birthday, and—gosh, all

sorts of things. I wouldn't have thought of it to-

day, except that Professor Bullfinch said some-

thing about his old friend, the geologist, coming

to visit us. Now that we're here, nothing's go-

ing to stop me."

Joe sighed. "Oh, I know. But trouble can

come to you out of a clear blue sky, Danny. Like

that time you promised Miss Arnold you'd never

15

meddle with the science experiments in class

again. Then, you dropped a little sulphur in

that test tube when she wasn't looking. Phew!

It took days to get the smell out of the class-

room."

"I just wanted to see what would happen,"

Danny said, indignantly. "But anyway, that's

got nothing to do with today. This time, we've

got flashlights, there won't be any trouble, and

nothing's going to happen."

He turned away. Before he could take an-

other step, something rang against the stones

above his head, shot out into the air, and landed

with a thump in the grass at his feet as if it had

dropped from the sky.

16

CHAPTER TWO

Danny's Choice

For a long moment, the young people stood mo-

tionless, staring. Then Danny stooped to pick

up the thing.

"Don't touch it!" Irene gasped.

"Why not?" said Danny. "It's only an old

hammer, after all."

He turned it over, examining it curiously.

Joe tilted his head back. "What'd I tell you?"

he said. "I didn't hear any plane. That thing

must have fallen from a flying saucer. Are you

sure it's just a hammer? Maybe it's a death ray

shaped like a hammer."

"I'm almost sure it isn't," said a strange voice.

Looking upward in astonishment, the three

saw a short, weatherbeaten man regarding them

from the top of the ridge. He was dressed in a

corduroy jacket patched with leather on the el-

bows, but there was nothing ragged or dirty

about him. He had the look of one who had

traveled far, an outdoorsman, or an explorer.

His hair was white above his sunburned face, but

17

"I'm a geologist.

his eyes were bright blue, sharp, and lively.

"I'm terribly sorry," he said. "I hope nobody

was hurt."

"We're all right," Danny answered.

The stranger climbed quickly down the ridge.

"I had just chipped out a fine little cephalopod,

and I laid my hammer on the rock above me. It

slid down."

He held out a lump of stone and the young

people could see that it had a faint marking on

it, or rather, in it: a small, coiled shape like a

snail-shell.

"That's what I found," said the man.

"That's a sifflepod?" said Joe. "It looks like

a snail."

"The cephalopods were molluscs, something

like—well—sea snails," the other said.

"Oh, then you're a fossil hunter?" asked Irene.

"Not exactly. I'm a geologist. But I can't

resist a nice specimen."

"I knew you were a geologist," said Danny.

"I could tell by the shape of your hammer. Are

you working at Midston College?"

"Oh, dear no," said the other, with a smile.

"I'm just visiting here. Although heaven knows

what Bullfinch must think. I knew I ought to

phone him, but when I got off that early train

and looked up at these hills, I thought to my-

20

self, 'What beautiful examples of sedimentary

rockl' I got out my hammer, left my suitcase in

the waiting room, and—well, here I am."

At the mention of Professor Bullfinch's name,

Danny snapped his fingers. "Now I know whoyou are," he exclaimed. "You're Doctor Tres-

selt, and you're coming to stay with us."

"I am undoubtedly Dr. Tresselt," said the ge-

ologist. "But I think you're mistaken. I'm go-

ing to stay with Professor Bullfinch. Not that

I wouldn't like to stay with you," he added, in

a kindly tone. "I'm very fond of children. I

have three or four of my own."

"I know," Danny said.

"You do? I didn't think my children had any

friends in this neighborhood."

"No, I mean I know you're going to stay with

Professor Bullfinch. I live with him. I'm

Eianny Dunn. My mother is his housekeeper."

"Well, I'm delighted to meet you," said Dr.

Tresselt, shaking the boy's hand warmly. "And

these are your brother and sister, no doubt?"

Irene giggled. "My name's Irene Miller, Dr.

Tresselt. I live next door to Dan."

"Her father teaches astronomy at Midston,"

Danny added. "And this is my friend, Joe Pear-

son."

"Nice to know you both," Dr. Tresselt said.

21

"Now, if you'll excuse me, I think I'll return to

the ledge. There are some very attractive fos-

sils—"

"Jumping catfish!" said Danny. "Wait a

minute, sir. I—I really think you ought to start

for town. If you got in on the early train. Pro-

fessor Bullfinch will be worrying about you. It's

past eleven o'clock."

"Hmm. Yes, I suppose you're right." Dr.

Tresselt shaded his eyes with his hand and looked

about. "Unfortunately, I haven't the faintest

idea how to get back to town. But never mind.

Bullfinch will certainly find me. He was always

very good at that sort of thing when we were in

school together. Goodbye."

And with that, he turned away.

"Dr. Tresseltl" cried Danny. "Gee, excuse

me, but—well, we know the way to town."

"Of course you do," the geologist beamed.

"An excellent idea. You run along and tell

Bullfinch where I am. He'll understand."

He waved his hand at them and started to

climb the ridge.

"What'll we do?" Irene whispered. "Just

leave him?"

"We can't," said Danny. "It wouldn't be fair

to the Professor. Anyway—he forgot his ham-

mer."

22

At that moment, Dr. Tresselt returned. "Myhammer," he said, apologetically. "Thanks

very much."

"Listen, Dr. Tresselt," Danny said, desper-

ately, "I know my mother's expecting you for

lunch. She'll be very disappointed. And I

know the Professor's looking forward to seeing

you. I really think you ought to come along with

us. Then you can come back up here this after-

noon, or tomorrow. After all, you are supposed

to stay for a week."

"Yes, that's true." Dr. Tresselt tapped the

hammer against his palm. "I mustn't be so self-

ish. .. . The fact is, you see, I'm afraid I some-

times let my interest in my work get the better of

me. You're quite right, of course."

He straightened, decisively. "You're a very

good conscience, Danny. I ought to hire you.

Let's go, then."

They started off together, directly down the

hill, knowing that sooner or later they'd come

out in the meadows above the town. But they

had only gone a short distance when Joe, point-

ing ahead, said, "Hey, look, Dan! That big

white oak on the point of rock. Isn't that the

one—?"

Danny glanced at it. There, sure enough, was

the tree which marked the site of the cave. He23

looked at his friends, and then back at Dr. Tres-

selt, strolling behind them and whistling hap-

pily. He heaved a deep sigh. He knew per-

fectly well that if the geologist saw the cave, he

would go no further.

Then he did one of the bravest things he had

ever done. "It's just an old tree," he said.

"Come on, let's get Dr. Tresselt home."

24

CHAPTER THREE

Channel 25

They went, first, to the railroad station to pick

up Dr. Tresselt's suitcase, and then took a taxi

home. Professor Bullfiiich came out to meet the

cab and greeted his old friend enthusiastically.

"My dear Alvin," he said. "Glad to see you.

Up to your old tricks, eh?"

"I couldn't resist the hills, Euclid," said Dr.

Tresselt. "Some beautiful limestonel If these

youngsters hadn't dragged me away, I'd still be

there."

Professor Bullfinch took off his glasses and

wiped them, chuckling. "I'm grateful to you,

all three," he said.

"But weren't you worried?" asked Irene.

"The train came in at nine o'clock. We thought

you'd have the police out looking for Dr. Tres-

selt."

"Oh, Dr. Tresselt always manages to find his

way back somehow," the Professor said. "He

was lost in the Navajo desert for three weeks,

once, but he found himself all right in the end,

25

and brought back a very important report on

rock formations, as well."

"I've heard about absent-minded profes-

sors . . .," Joe whispered to Danny.

The Professor overheard him. "Not absent-

minded, Joe," he said. "People say that of sci-

entists because they don't understand how fas-

cinating our work can be. It can absorb your

attention so that you forget everything else. Dr.

Tresselt is far from absent-minded in everyday

affairs—I've never known him to wind up the cat

and put the clock out, for instance—but when he

is at work on a project, he tends to forget the rest

of the world."

Joe blushed. "I'm sorry," he said. "I guess

I know what you mean. It's the way I am when

I'm working on a poem, for instance."

"Exactly," said Dr. Tresselt. "In fact, scien-

tists and artists are alike in many ways."

They all went into the house, and Mrs. Dunn,

a comfortable, jolly-looking woman with hair as

red as her son's, shook Dr. Tresselt's hand.

"Professor Bullfinch told me we might not see

you until dinner-time," she said. "Fortunately,

I didn't believe him. Lunch will be ready in a

few minutes. Come along. Dr. Tresselt, and

I'll show you to your room."

26

The three grownups went upstairs. Danny

sighed, jamming his hands deep into his pockets.

"Well, I'm glad we got him home," he said.

"But I sure hated to leave that cave."

"What?" said Joe. "You mean that the tree

I saw really was the one that marked where the

entrance was?"

"I knew that," Irene said, quietly. "And

Danny, I think it was—well—noble of you."

Danny shrugged, kicking at the rug with one

toe. "Yeah, I must have been sick or something.

I'll just never find the way back to that spot."

"Yes, you will," Irene smiled mischievously.

"I dropped back, you know, and when I did I

spotted the cave entrance. So, as we went down

the hill, I marked the trail by breaking twigs so

that they pointed back toward it, and by tying

knots in the long grass. We can find the way

easily."

Danny brightened. "Gosh, Irene, you're

great! I was so busy with Dr. Tresselt that I

never even thought of doing that."

"He's nice, isn't he?" Irene said.

"There's one thing," said Joe. "How could

you tell that was a geologist's hammer? I didn't

know geologists went around hammering

things." He scratched his head. "To tell the

27

truth, I don't know what they do go around do-

ing."

"Geologists study the earth," Danny replied.

"They study the rocks, and how mountains were

formed, and how old the earth is, and what hap-

pens to rivers and lakes and oceans. They have

to know all sorts of sciences—botany, chemistry,

physics, mineralogy. They have these special

hammers, with narrow heads and sharp picks on

them, so they can take samples of rocks and min-

erals."

He turned down the long hall that led to Pro-

fessor Bullfinch's private laboratory, which was

built on to the back of the house. "Let's go look

in the Professor's library," he said. "I want to

see what Dr. Tresselt meant when he talked

about 'sedimentary rock.'"

"I'll join you later," Joe said. "I've—um

—

got dirt all over my hands. I'll just run into the

kitchen and wash up."

He left them, and Dan and Irene went on to

the laboratory, Irene remarking, "Joe must have

sunstroke or something. That's the first time

I've ever heard him say right out that he wanted

to wash his hands."

The laboratory consisted of two rooms, one

small one fitted with shelves on which were

28

books, notebooks, and files, and a larger one in

which were stone-topped tables, stools, and all

the varied equipment the Professor needed for

his researches.

"Hey, look!" Danny said, as they entered this

large room. "Professor Bullfinch has a portable

TV set."

On one of the lab tables stood a small metal

case with a glass screen on one side about a foot

square, and a blunt, cone-shaped projection on

the other.

"I didn't know the Professor watched televi-

sion programs," said Irene.

"Oh, he must be using this for experiments,'*

Danny said. "Hmm ... I wonder if it's one of

those color sets."

He examined the top of the case, in which

were set tuning dials and switches, like those in

an ordinary television set. "This dial must show

the channels," he said. "But gosh! this must be

an experimental model of some kind, because it

goes up to Channel 75."

He studied the switches for a moment and

then snapped one of them. The set began to

hum softly, and the screen glowed.

"Let's try Channel 25," he said. "Maybe it

comes from some foreign country."

29

He twiddled the knobs until a picture sud-

denly came into focus. He and Irene stared at

it.

It was obviously a kitchen, although every-

thing was shadowy and indistinct, and no details

showed. They could make out a sink, a window,

and part of a table. It looked very much like a

shadowgraph, in which only the silhouettes of

things showed against the light.

"It's not very clear, is it?" Irene said. "And

it's certainly not in color."

"I'll see if I can get it a little sharper," said

Danny. He turned one of the dials.

"Look!" Irene cried. "The picture's mov-

ing."

As the dial turned, the scene itself moved, as

though the invisible camera were traveling. All

at once something else came into view.

It was unmistakably a refrigerator. The door

stood open. A figure straightened up, holding

something which they decided was the leg of a

chicken. The figure did a little jig and then be-

gan to gnaw at the chicken leg.

"You know," said Dan, "there's something

awfully familiar about that television actor, even

though all you can see is his outline."

Irene put her hands over her mouth to stifle a

scream of laughter.

"The hair—the long nose—the way he

moves," she said. "Of course he looks familiar.

It's Joe!"

II

CHAPTER FOUR

The See-Ray

Danny rubbed his nose thoughtfully, as he gazed

at the image on the screen. "I think you're

right," he said, slowly. "And you know some-

thing else? I don't think this is a television set."

"That is correct, my boy," said the Professor,

from behind him.

He had come into the laboratory that instant,

with Dr. Tresselt, and he walked over and put

a friendly hand on Danny's shoulder.

"Gosh, Professor, I didn't mean to fool with

it," Danny said. "But it does look just like a

portable television set, and I thought—

"

"No harm done," said Professor Bullfinch.

"I can understand your confusion. As a matter

of fact, I was just about to demonstrate it to Dr.

Tresselt, so you've saved me the trouble of turn-

ing it on."

He beckoned to the geologist to come closer.

"Look here, Alvin. It is set for a distance of

twenty-five feet."

"Oh," said Danny. "Not Channel 25."

32

"No." The Professor laughed. "So far, this

experimental model has a range of about sev-

enty-five feet. What you are seeing now is—um—the kitchen on the other side of that wall."

Dr. Tresselt stooped to peer into the screen.

"Very interesting," he said. "So this is the C-

ray.

"A little joke of my own," smiled the Pro-

fessor. "5^e-ray."

"A kind of X-ray, actually?"

"Well, a radiation operating at the same short

wave length as X-ray. But I produce it so that

a much smaller amount is easily detectable. I

can thus time the reflection of the rays almost

like—well—radar. As you see, the screen is sim-

ilar to that of a radarscope. But the sensitivity is

so great that I can detect it easily, and thus there

is no radiation danger."

"I see," said Dr. Tresselt. "The same job

with less juice, you might say."

"Exactly. I thought it might have some value

in geology, or mineralogy, since you can, in ef-

fect, see right through solid rock with it."

The geologist shook his head. "We'd have to

try it. It might develop all sorts of bugs under

field conditions. And I doubt that it would be

able to select between layers of, say, limestone

and sandstone."

33

"That's why I wanted to show it to you," said

the Professor. "I thought you might take it with

you on your next expedition."

Dr. Tresselt was looking at the screen again.

"Whatever else it does, it certainly shows up ice-

box raiders ver)' well," he said. "I presume

that's your friend Joe?"

"Yes, it is," Danny said. "And—well, don't

you think. Professor, that if the machine can pick

out Joe and what he's eating as well as it does,

that it could show fossils, or crystals, in rocks?"

The Professor stroked his chin. "Not quite

the same, Dan," he replied. "In this case, the

ray is probing through a solid wall to pick up

objects in empty space—the kitchen. But Dr.

Tresselt isn't sure it will be able to select objects

buried in another solid, like stone."

"It was good thinking, though," said Dr.

Tresselt. "You certainly are interested in

science, Dan. How about you, Irene? Don't

you sometimes feel left out of things?"

Irene looked indignant. Before she could an-

swer, Danny said, "Gosh, no. She knows more

than I do about some branches of science. Not

very much, though," he added, hastily.

"I'm going to be a physicist when I go to col-

lege," Irene said. "You know there are womenwho are scientists

—

"

34

Dr. Tresselt lifted his hands apologetically.

"I'm sorry," he said. "You're right. I spoke

without thinking."

Irene looked happier.

"She's so crazy about science, she even wears

it," Danny grinned.

"I'm afraid I don't understand," said the geol-

ogist, looking perplexed. "How can you wear

science?"

Professor Bullfinch snapped off his C-ray ma-

chine, with a chuckle.

"I think I know what Danny means. Irene

has been making up a science charm bracelet.

Aren't you wearing it today, my dear?"

"No, Professor, I forgot it," said Irene.

"All the charms on it stand for different

branches of science," Danny explained. "She's

got a four-leaf clover that stands for botany, and

a lump of iron—one of the elements—for chem-

istry. What else is there, Irene?"

Irene frowned. "Well, there's a tiny magnify-

ing glass for microscopy, and a computer switch

for mathematics, and a little nut and bolt for

engineering, and a dried cocoon for insect stud-

ies, and on my birthday my father gave me a tiny

gold tag with Einstein's equation—E = MC^

—

engraved on it. That's for physics."

"What a list," laughed Dr. Tresselt. "Excel-

35

lent! Sounds very complete. But what have

you for geology?"

"Gee, I haven't anything yet. What do you

suggest?"

"We must try to find her a little fossil, or per-

haps a handsome little crystal of some sort, eh,

Bullfinch?"

The Professor nodded. Before he could re-

ply, however, Joe came into the laboratory.

"Hello, everybody," he said. "I just came in

to say goodbye. I've got to go home for lunch."

Danny looked innocently at his friend.

"Hands all washed?" he asked.

"Sure. Why?"

"But Joe—you don't mean to say you still have

room for lunch?" Irene cried.

"Why not?" Joe said, but his face began to

turn red.

Danny put his fingers to his forehead. "I amin contact with the spirit world," he said, in a

mysterious voice. "I am now receiving a mes-

sage from beyond—from a ghost—from the

ghost of a roast chicken. It tells me you went

into the refrigerator while my mother was out

of the kitchen, and that you took a drumstick

and ate it. ..."

Joe gave a long whistle. Then he shrugged.

36

"Okay," he said. "I confess. What did you do,

peek through the window?"

"Easier than that," said Danny. "We watched

you through the wall."

"Uh-huh," Joe grunted. "Why didn't you

walk right through, then, and show me where

the mayonnaise was?"

"It's true, Joe," said Irene. "Ask the Profes-

sor. We watched you with his new Cray."

"Nobody's safe any more," Joe mumbled. "I

always got into trouble with Danny. Now, I

can't even trust the Professor. Next thing you

know, there'll be rays to make sure you do your

homework, and rays that make you wash behind

the ears—

"

"Come, now, Joe," said Professor Bullfinch,

taking out his pipe and filling it. "Things aren't

quite that bad."

"Not yet, maybe," Joe said, gloomily. "I

should think you scientists could find something

better to invent than a ray for spying on a poor

hungry kid like me . . . pale, and thin . . . just

picking up a few crumbs. ..."

The others burst into laughter. The Profes-

sor said, "Joe, I give you my word I didn't invent

the C-ray to make you unhappy. We'll never

use it to watch you again."

37

"That cheers me up," said Joe, looking sadder

than ever.

"I hate to break up the National Research

Council convention," said Mrs. Dunn, putting

her head into the room, "but lunch is ready."

Danny said, "Oh, Mom. Do you think Joe

and Irene—

"

"I've already called their mothers," Mrs.

Dunn said, placidly. "There's enough lunch

for everyone. Joe won't need quite as much as

the rest, as he's already had part o£ his."

"Oh, help!" wailed Joe. "How about that?

She's got a Cray, too!"

Irene sniffed. "Hmfl You ought to knowthat mothers don't need science to find out

things. You probably left the drumstick on the

table."

"On a chair, as a matter of fact," said Mrs.

Dunn. "And his face is greasy. Come on, every-

one."

38

CHAPTER FIVE

Makine Plans

Lunch was a cheerful affair. They all sat round

the long, oval table in the sunny dining room,

and feasted on cold chicken, ham salad, swiss

cheese, and some of Mrs. Dunn's famous choco-

late cake. When they had eaten all they could

hold, and the grownups were sipping their cof-

fee, Joe said, "That's one kind of ray I hope they

never invent—an eating ray."

"Good heavens, Joe," said Mrs. Dunn.

"What on earth made you think of that?"

"Oh, the Professor's new C-ray," Joe ex-

plained. "I just hope they never come up with

anything to take the place of eating."

"I don't think you need worry," said the Pro-

fessor, pulling out his old pipe. "Even if any-

one succeeded in inventing such a device, I don't

think most people would care for it. Food is

too much fun."

"I agree," said Joe. "Boy! There are times

when I get the feeling that science develops

things that are supposed to be good for us, but

that just make trouble."

39

Dr. Tresselt's blue eyes seemed to throw out

sparks of amusement. "I know how you feel,

Joe," he said. "But my stars, boy, nobody can

be alive and never have any trouble ! Being alive

is just meeting troubles every day and overcom-

ing them. Just to stand up straight against the

pull of gravity is a fight, isn't it?"

"I think Joe would rather spend his days ly-

ing down," Irene giggled.

"Nothing wrong with that," Joe said. "You

know, I can be as lively as anyone else, but there

are times when I'd like to run away and live in

a cave and be a hermit, and not have to—

"

Danny's head snapped up. "Joe," he said,

"you're brilliant."

"I am?" Joe raised his eyebrows.

"Yes, sir. I always knew it."

"You did?"

"That's a wonderful idea."

"It is, huh?" Joe blinked. "I am proud and

humble. Uh . . . which particular one of mymany ideas are you talking about?"

"Why, mentioning the cave, of course. I'd

forgotten all about it. How about going this

afternoon?"

Dr. Tresselt had pricked up his ears. "Cave?

What cave?"

"Oh, one Danny discovered," said Irene.

40

"We were going to explore it this morning, when

we found you. Danny made us leave it—he said

it was more important to get you home."

Professor Bullfinch opened his eyes wide at

this, but before he could say anything, Dr. Tres-

selt said, crisply, "What's it like? Shallow?

River running out of it? Carbonate of lime con-

cretions?"

"Gee, Dr. Tresselt, I really don't know much

about it," Danny answered. "You see, I found

it last spring. I didn't have any light with me so

I couldn't really explore it. But it didn't look

shallow—it seemed to go 'way in. There's no

river, and I don't know about carbonate of lime."

Dr. Tresselt rose to his feet. "Let's go," he

said.

"Hold on a minute, Alvin." Professor Bull-

finch caught him by the wrist. "I absolutely for-

bid your dashing off into the hills this afternoon.

I have arranged to introduce you to Herbert

Jaffe, the chief of Midston's Geology Depart-

ment—a great admirer of your work. He, in

turn, is giving a faculty tea party for you, and

he wants to take you around the school."

"Oh—heckl" said Dr. Tresselt, with a de-

spairing look. "No way out of it?"

"Absolutely none. While you're here, you've

got to meet some of these men. They are look-

41

ing forward to it." The Professor tapped his

chin with his pipestem, thoughtfully. "How-

ever, tomorrow—

"

"Hooray!" Danny burst out. "An expedi-

tion!"

"Take it easy, Danny," cautioned the Profes-

sor. "I didn't say anything about an expedition.

But we might just stroll up there in the morning,

and—er—sort of glance inside. . .."

"We can call it the BuUfinch-Tresselt Under-

ground Expedition," said Irene. "We'd better

make a list of all the things we'll need."

"Rope," Danny said, taking out his pencil.

"And flashlights and spare batteries."

"A first-aid kit," Irene said.

"You'll need provisions, too," Joe put in.

"Aren't you coming?" Danny said.

"Oh, sure, you'll need somebody to help you

eat them."

"Better put down warm clothing, too," said

the Professor. "It'll be a lot chillier inside than

out in the sun."

"I have another idea, Professor Bullfinch,"

said Danny. "You could bring along the C-ray.

You said it ought to be tried out in the field.

This would be a way of doing that, wouldn't it?"

"Fine," said the Professor. "A good thought.

42

We ought to be able to check whether it picks

up discontinuities in a homogenous mass."

"I'm almost certain it won't register fossil lay-

ers," Dr. Tresselt said, shaking his head. "I

don't see how—

"

"Tut, tut, my dear man," the Professor began.

Mrs. Dunn interrupted him. "Just a mo-

ment. Nobody's asked me what I think."

"Oh, Mom!" Danny cried. "Please say we

can go. Please/'

"Hmmm. I don't know."

"I really don't think there will be any danger,"

said the Professor. "In the first place, both Al-

vin and I have had considerable experience in

speleology."

"It's not your spelling I'm worried about,"

Mrs. Dunn said.

"Speleology is the scientific study of caves,"

Professor Bullfinch smiled. "Both of us have

done a good deal of caving, and we'll take all the

necessary precautions. In the second place, I

feel that Danny deserves this trip. You may not

realize it, but this morning he did something

that showed great strength of character. You

heard what Irene said: he was about to explore

the Cave, but then he saw to it that Tresselt got

here, instead. I don't think Dr. Tresselt would

43

have given up an interesting project like that.

I'm not even sure I'd have done so myself."

"It's a good thing he didn't mention it this

morning," Dr. Tresselt said, with a chuckle.

"I probably would have camped on the spot."

"That's what I mean," Mrs. Dunn said, drily.

"I'm not too worried about Danny. He knows

how to take care of himself, and I'm sure I can

trust him to be cautious. It's you two grownups

I'm worried about."

"Us?" The Professor looked blank.

"Just so. You're liable to get these youngsters

into that cave and then start one of your investi-

gations and forget all about them. They might

manage to get home—but will you?"

The Professor and Dr. Tresselt looked at each

other and then at Mrs. Dunn. They both had

rather foolish expressions, like overgrown

schoolboys being scolded by the teacher.

Irene put in, "Oh, Mrs. Dunn, we'll promise

to take care of them and see to it that they don't

get into trouble."

Mrs. Dunn's eyes twinkled, and she got up and

began to clear the table. "Well," she said, "I'll

give my permission for Danny to go, in that

case."

"I'm going home right now," said Irene,

44

jumping up, "and ask my mother, but if you say

it's all right, she will too."

"Okay," Danny said, picking up a pile of

dishes to take to the kitchen. "Then come back.

You too, Joe. We've got lots of plans to make

and things to get ready for tomorrow. TheBullfinch-Tresselt Underground Expedition is

on its wayl"

45

CHAPTER SIX

Slide into Darkness

Although the night was damp and cloudy, the

morning dawned bright and clear and the ex-

pedition hiked up through the woods under a

brilliant sky. As Danny remarked, it wouldn't

make much difference to them what kind of day

it was once they got underground, but it raised

their spirits immensely before they started.

They found the way without difficulty, follow-

ing Irene's blazed trail. As they approached the

big oak tree. Dr. Tresselt stopped and pointed to

a deep gully cut in the earth like a wagon road.

"Many of these caves in limestone hills were

carved out by flowing streams," he said. "That

gully shows where the stream may once have

come out."

"And there's the cave itself," Danny cried, in

excitement.

They could see that the oak tree stood on a

rocky point formed by two great slabs leaning

against each other. Below was a black opening,

like the entrance to a teepee. They climbed up

46

to it, and then paused to pull on sweaters or

heavy jackets.

They were all variously loaded down. Dr.

Tresselt carried a powerful battery lamp belong-

ing to the Professor; Professor Bullfinch had

another such lamp and his C-ray; the three

young people each wore a knapsack and carried

a good flashlight. Irene had a first-aid kit in her

pack, and spare batteries for all the diEerent

lamps. Joe's knapsack was stuffed with sand-

wiches, chocolate bars, and cookies. Danny

opened his pack and took out a square metal box

with a handle at the top, a pair of earphones, and

what looked like a microphone on a cable at-

tached to it.

"Well, well," said Dr. Tresselt. "A Geiger-

Miiller counter, eh? Planning to do a little pros-

pecting for uranium?"

"I doubt there's any around here, Danny,"

said the Professor, gravely.

"It's not for that at all," Danny replied, check-

ing over the instrument and replacing it in his

pack. "But since this is a scientific expedition,

we ought to do the whole thing scientifically.

So this is for finding our way back."

"I don't think I quite understand," the Profes-

sor said. "How is a Geiger counter going to

help?"

47

'This is for finding our way back."

"Well, I borrowed this from Professor Blum,

in the Physics Department, yesterday," Danny

said. "And I also got from him some thorium

nitrate crystals. They're mildly radioactive,

you know, and they'll register on the counter and

make it click rapidly. I've got 'em in this little

box. Every time we come to a place where

there's more than one way to go, I'll drop a few

of them. Then, when we come back, we can

pick up our trail with the counter. See?"

The Professor rubbed his bald head. "I see.

But wouldn't it have been easier if you had just

brought along a small can of white paint and a

brush?"

"Easier?" Danny shook his head, scornfully.

"Gosh, no! Opening and closing a can of sloppy

paint? And messing around with a brush?"

"As it happens, I brought along a piece of

chalk," Dr. Tresselt observed, mildly.

"Chalk? But gosh, Dr. Tresselt," Danny

wailed, "that isn't scientific at all!"

"All right," said Professor Bullfinch. "We'll

let you do it your way, Dan, since you've madesuch careful preparations. Now, are we all set?"

"Right!" said Dr. Tresselt.

"I'm ready," said Joe. He took a notebook

and a pencil out of his pocket. "Ten a.m. Theexpedition arrived at the cave entrance and pre-

49

pared to make its way to the very center of the

earth."

"Sounds exciting," said the Professor. "Only

I don't think we'll be going that far down."

"It's what they call 'artistic license,' " Joe ex-

plained. "I've decided to write a report about

the trip for the school magazine, and I have to

make it seem dangerous even if it isn't." Hegulped nervously. "Anyway, I sure hope it

isn't."

"I'm ready," said Irene. She jingled the

charm bracelet, which this morning she was

wearing on her wrist. "I'm going to see if I can

find something interesting to represent geology

on my bracelet."

"Let's go, then," said the Professor.

He stepped forward, snapping on his lamp.

Danny was right at his heels, and the others

pressed close behind.

They stood in a rock chamber with high, arch-

ing walls. Under the beams of their lights the

wall shone like glass, and here and there clusters

of white crystals flashed out. The floor was cov-

ered with loose stone and gravel. The ceiling,

arched and craggy, sloped down toward the back

of the cave where it was lost in darkness.

Dr. Tresselt bent and picked up what looked

like a round, white pebble. "Carbonate of

50

lime," he said. "The result of the passage of

water through the limestone."

Irene and Joe drew close to look. Danny,

after a glance, went to the back of the cave.

"Professor Bullfinch," he called, his voice echo-

ing in the chamber. "There's an opening here.

Plenty big enough for you to stand up in."

The Professor hastened to join him, and to-

gether they shone their lights into the space.

"It's a real tunnel, all right," he said.

Its floor slanted steeply downward, and was

covered with loose gravel. The Professor took

a cautious step or two, and then said, "I can heai

something trickling. There may be a stream

down there."

"Oh, boy!" Danny said. "A secret under-

ground river!"

He darted forward. His foot slipped in the

gravel, and he lost his balance. He grabbed for

the nearest support, which happened to be the

front of the Professor's jacket.

The Professor went plunging down the slope,

with Danny clinging to him. Somehow they

managed to keep from falling. Sliding and sway-

ing, they raced downward, their lights darting

crazily as they waved their arms to keep their

balance. Then, all at once, they hit a patch of

wet clay.

The Professor's heels went out from under

him.

"I can't—" he yelled.

Thump! Down he went, with Dan on top of

him.

There was a long pause. At last, in a muffled

voice, he finished: "—keep my balance. Would

you mind taking your elbow out of my ear,

Dan?"

52

CHAPTER SEVEN

The Underground Waterfall

They disentangled themselves and got to their

feet. The back of the Professor's coat was cov-

ered with blue clay, which Danny tried vainly to

wipe off.

"I'm awfully sorry," the boy said. "It was all

my fault. I shouldn't have rushed out ahead of

you like that."

The Professor shook his head. "There are

times when you are rather—uh—sudden, Dan,"

he said, mildly. "However, this gravel is tricky

stuff. And in cave exploring, I suppose we must

expect a few spills."

Fortunately, their lights weren't damaged.

The Professor looked about for his C-ray. It lay

close at hand, one corner buried in soft clay.

"It seems to be all right," said the Professor,

examining it. "I hope none of the tubes have

been broken."

He was about to snap it on and try it, when

from the cave above them came a hail from Dr.

Tresselt.

53

"Ahoy, Bullfinch! Are you down there?"

The Professor turned back and shouted, "Yes!

Come on down."

Gravel began rattling along the slope and

within a few moments their friends had joined

them.

Dr. Tresselt said, "Do you really think it was

wise, Euclid, to go on ahead without telling the

rest of us where you were going?"

"Don't be annoyed, my dear chap," the Pro-

fessor replied. "In theory you are absolutely

correct, but this was a case where theory and

practice didn't go together. I didn't even have

time to yell 'Help!'"

Danny had been examining their surround-

ings, and he now broke in, "You were right. Pro-

fessor. There is a stream."

They crowded round him. The clay bank

ended in a flat strand of stone, below which

flowed a shallow river some nine or ten feet

wide. Smooth boulders stuck up out of it, and

on its other shore rose a wall of glistening rock.

The water was black in the lamplight, but when

Joe shone the beam of his flashlight directly into

it they could see that it was as clear as glass.

"Hey, there are fish in this stream," Joe said.

"But golly, they look awfully pale. Aren't they

well?"

54

"They're just bleached out from living in the

dark," Irene said, leaning over to watch the slen-

der white forms that darted in and out of the

circle of light. "Do you think they're blind, too,

Dr. Tresselt?"

The geologist nodded. "Possibly," he said.

He wasn't looking into the water, however, but

at the walls of the cavern. "You know," he went

on, "I think we are looking at the thing which

dug out these caves in the first place."

"We are?" Danny cried. "Where is it?"

"A machine?" said Joe. "Or a prehistoric

monster?"

"A kind of prehistoric monster," Dr. Tresselt

chuckled. "There it is—right at your feet."

Joe jumped back.

"I know what you mean," said Danny, grin-

ning. "The river!"

"Just so. The river cut its way through the

soft limestone—of course, when I say 'soft' I

mean that only in terms of other rocks—during

millions of years, eating it away and making a

bigger and bigger passage for itself."

"Then why doesn't it still come out at the

upper cave, where we entered?" Danny asked.

"We saw the dry bed where it used to be, re-

member. What made it stop running up

there?"

55

"I think there must have been other streams

tunnehng below it," Dr. Tresselt replied. "Orpossibly an earthquake shifted the rock. Hard

to say. Whatever the reason was, the bed of the

river collapsed and the stream level dropped."

"Where do you think it comes out now?"

Irene said. "Somewhere in the valley?"

"Maybe at the reservoir," Danny suggested.

Dr. Tresselt flashed his light, first down the

stream, then up. "It's difficult to say. It could

come out a long way below Midston." Hewalked a little way upstream and paused. "Shhl

Don't I hear something?"

They cocked their heads. At last, Irene said,

"I can hear a kind of hollow, roaring sound."

"Yes, so can I," said Danny.

"A waterfall?" asked Professor Bullfinch.

"I wouldn't be surprised," Dr. Tresselt an-

swered.

"Let's go see," Danny said. And before the

others could answer, he was already trotting

along the flat stone shore toward the distant

sound.

"Hey, waiti" called Joe. "Maybe it's too

risky. Maybe we'll be washed away. Maybe

it's—oh, what's the use?" he finished, shrugging.

"Let's go."

"Yes, since we've come this far," the Professor

56

said, smiling, "I must say, I wouldn't mind see-

ing an underground waterfall myself. If that's

what it really is."

Irene and Joe soon caught up with Danny and

the three made their way along the bank of the

river, side by side. The water clucked and

gurgled softly. Joe kept shining his light into it,

and reflections shot up and sparkled from the

walls and roof.

"What I'd like to do," Danny said, "is bring a

boat here and travel right down the river.

Wouldn't that be fun?"

"Fun?" Joe snorted. "We'd probably end up

coming out of somebody's water faucet."

"Oh, Joe. You're always looking on the dark

side of things," Irene protested.

"Well, what of it?" Joe gestured with his light

at the gloomy cavern around them. "Where

else would you look, down here?"

"I suppose the chances are that it might be

impossible to get all the way downstream," Irene

said. "The tunnel might get too low for a boat

to get through. Or the water might drop downdeeper and deeper."

"To the center of the earth," Joe muttered.

"And then we'd be boiled to death. Boiled Joe

with cave sauce. What a way to end!"

Danny laughed. "Well, don't start planning

57

your own menu, Joe. We haven't even got a

boat."

Joe shook his head. "If I know you, you'll

probably invent one before we get out of here,"

he said. "Nothing but trouble."

The passage grew smaller so that they now

had to go in single file. Columns of stone, some

of them polished and smooth, rose before them

and they had to pick their way slowly. The air

grew damp and a cool, faint breeze touched their

faces. The roaring, rushing noise was so loud it

seemed to shake the very rocks.

All at once Danny stopped, so abruptly that

Irene bumped into him. She looked over his

shoulder. Then she turned to Joe. "Look at

this!" She had to yell to make herself heard,

even though he was right behind her.

In the light of their combined torches, a mag-

ical sight appeared. A curtain of diamonds was

strung before them. Its foot was white foam in

which floated rainbow-colored bubbles the size

of soup bowls. It was not very high, but it had

a majestic look, pouring from the roof of the

cave and winding away between the ledges of

shining stone.

"It's like fairyland," Irene said. The boys

nodded soberly.

As they stood gazing in wonder, the two men58

caught up with them. They, too, stared at the

lovely waterfall in silence for a long time.

The Professor gave a long sigh. He shone his

flashlight along the top of the falls, and they

could see that the rocky roof came down almost

to the water. The walls closed in, too, on either

side.

"It looks as though this is the end of the trip,"

he said. "This is as far as we can go."

59

CHAPTER EIGHT

The Bridge of Stone

They all moved back a little way to avoid the

spray which was beginning to soak them, and sat

down on a ledge from which they could look

about in comfort. Professor Bullfinch pointed

to the roof.

"Icicles!" Joe exclaimed.

The roof here was composed of flat slabs of

stone, veined with darker green and pale blue.

From it hung hundreds of what appeared to be

pointing fingers, some of them a few inches long,

some nearly a foot.

"Stalactites," Danny said. "I've read about

them. They're formed by water dripping from

above, aren't they. Professor?"

"Yes. The water seeps through minerals and

leaves deposits of them as it evaporates. It may

take about ten years for an inch-long stalactite of

the thickness of those on the roof to form.

Thicker ones may take longer. Those, for in-

stance— '*

He pointed with his lamp at the wall, some

60

distance away and to one side of the waterfall.

They saw several immense stalactites hanging

down, perhaps two feet thick and as tall as a

man.

"Those may have taken a hundred thousand

years to form," said the Professor.

"Whew! The ones up on the ceiling are

babies, then," Joe said. "Thirty- or forty-year-

old babies."

"Yes. Probably they haven't grown longer

because there is a slight air current here caused

by the rush of the falls. That would make the

dripping water evaporate too quickly."

Danny got up. "I'd like to look at those big

stalactites," he said. He wandered off, his light

throwing strange shadows from the stone and

water.

Joe pointed his own flashlight in Danny's di-

rection. "Look, Professor," he said. "There's

an upside-down stalactite. One that got mixed

up and grew the wrong way."

A pointed column grew out of the floor not

far from where Danny was at that moment walk-

ing. It was almost as high as the boy himself,

with a dazzling white streak down the side of it,

like snow on a thin, steep mountain.

"Ah, that kind we call stalagmites," said Dr.

Tresselt. "They are caused by water dropping

61

on the floor and building secretions of minerals

from the ground up."

As he spoke, Danny let out a yell. His voice

echoed in the chamber above the noise of the

water.

Joe sprang to his feet. "A stalactite's got

himl" he said.

The others stood up, too. They could see

Danny waving his light back and forth, as if to

signal them.

"I believe he's found something," said the

Professor.

He had, indeed, found something. Whenthe others joined him, he pointed triumphantly.

Behind the stalactites, which hung almost to the

floor, was an opening. It was very small, but one

person at a time could enter it on hands and

knees.

"It gets bigger after a little way," he said. "If

you shine your light in, you can see that it's a

kind of split in the rock, and there's a ledge that

goes up, almost like a stairway."

Dr. Tresselt immediately bent over to peer

into the opening. "Ah, yes, I see," he said.

"Well, well. A most interesting forma-

tion. . .."

He crawled through. At once, Danny fol-

lowed.

62

The Professor said, doubtfully, "I wonder if

we ought to wait—

"

Dan's face reappeared in the entrance.

"Gosh, come on," he cried. "It's terrific! All

sparkling— I"

Professor Bullfinch nodded. "Very well," he

said. "I suppose we can push on for a while

longer. Go on, Irene, and you, Joe. I'll bring

up the rear."

The ledge mounted steeply through a high,

narrow crack in the stone. It was jagged and

slippery, but they could find foothold enough to

keep going up. The sides were streaked with

white crystals that twinkled and flashed like

snow under their lamps. They climbed for

about five minutes, and then Dr. Tresselt, still

in the lead, called back, "Be careful when you

get up here."

"What have you found, Alvin?" shouted the

Professor.

"The ledge widens up here," replied the geol-

ogist, "but one wall opens out. You'll see when

you get here. Just keep to the left and watch

your step."

Danny clambered up the last few yards that

separated him from where the geologist was

standing. The rock face on his right ended in

empty space. The ledge broadened out and

63

sloped slightly inward, and there was enough

room for him to stand safely beside Dr. Tresselt.

As the others came up, Dr. Tresselt flashed his

light out into the dark void on their right.

"There's our river again," he remarked.

Some twenty feet below where they stood was

the water, a black mirror vanishing into a cleft

in the stone.

"You see, Dan?" said Irene. "That's one rea-

son it might be hard to get downstream in a boat.

The river keeps going into tunnels like that one,

where there wouldn't be room for a boat to stay

on the surface."

"You could use a submarine," Danny said.

"Or a skin-diver's outfit. Don't they sometimes

do that. Dr. Tresselt?"

"Yes," said the geologist. "In a place in Eng-

land which has the rather odd name of WookyHole, skin-divers have managed to get to almost

a dozen caves which are strung out along an

underground river, something like this one."

Danny said, "The ledge is still here, and it's

almost as wide as a sidewalk. Let's keep going."

The Professor pulled out his watch and

glanced at it. "We've been underground for

almost an hour," he said. "I know we ought to

turn back but I must confess I find this abso-

lutely fascinating. What do you say, Alvin?"

64

"Oh, let's go on for a bit," said the geologist,

turning to examine the wall behind them. "I'd

like to see some more of these caves. You know,

I suspect that a certain amount of mud was car-

ried through here at one time. Look, there are

some darker deposits in the limestone."

He chipped a few bits out with the sharp pick-

end of his hammer, and then moved on after the

young people.

Danny had taken the lead, and he went along

boldly, looking about with great interest. The

ledge began to grow narrower. The walls fell

away on either side and he found himself in a

larger cavern, the roof of which vanished into

darkness. The ledge ended at a gap, some nine

feet wide and tapering toward the bottom, far

below, where the river still trickled. The gap

looked as though a giant had split the rock with

his ax. On its other side was a fairly wide shelf,

and then the mouth of another tunnel. The

gap was spanned by a mass of rubble which had

fallen from the roof and was jammed into the

triangular space, and across the top of it, like a

rude bridge, lay a slab of solid stone about two

feet wide and several inches thick.

Irene looked doubtfully at the block of stone.

"What do you think, Dan?" she asked. "Will it

hold us? Can we get across?"

65

Danny scratched his freckled nose. "It's got

to," he said. "I don't want to go back until we've

seen as much as we can."

He took off his knapsack, swung it by the

straps and threw it across to the shelf on the

other side. "There," he said. "Now I've got

to get across."

He stepped cautiously out on the slab.

"Oooh, I can't look," said Joe.

Dan held his breath, but nothing happened.

Then he walked lightly and swiftly the rest of

the way until he was standing beside his pack.

"It's easy," he called. "Come ahead."

Irene tossed her own pack over to him, and

walked across, trying not to look down.

Joe said, "You know, I don't really want to

do this. Couldn't I just wait here and sort of

think about things while you're exploring?"

"What about those notes you're taking for the

story you're going to write?" said Danny, "Are

you going to say, 'The expedition descended

into the depths and left me behind because I was

scared'?"

"Not a bad idea," groaned Joe. "Oh, all

right. Catch the pack."

He threw it over and Danny put it beside the

others. Then Joe, gritting his teeth, made the

crossing.

66

As soon as he had done so, he pulled out his

notebook. Holding it on his knee, with his

flashlight tucked under his chin, he began to

write.

Danny looked over his shoulder.

"What is he saying?" Irene asked.

Joe read aloud: "At eleven-fifteen a.m. I

heroically led the expedition across an impassa-

ble bridge."

"I have a feeling there's something wrong with

that sentence," Irene giggled.

Just then, the two scientists emerged on the

ledge on the other side of the gap.

They were deep in talk. Danny was about to

call out to them. Before he could do so, how-

ever, and without for a moment hesitating or

stopping their conversation, Dr. Tresselt

marched right out on the bridge, and the Pro-

fessor followed at his heels. Neither of the men

seemed to notice anything out of the ordinary,

so absorbed were they in their discussion.

"—the lime carbonate concretions would

seem to indicate a steady flow of water down that

fissure," Dr. Tresselt was saying.

"Perhaps," replied the Professor. "On the

other hand, isn't it possible that it represents a

fracture, possibly of seismologic origin, and that

the concretions—

"

67

With a crash the whole mass collapsed.

At this instant, there was a faint rumbling

sound.

"Hmm," said Dr. Tresselt. "Did you hear

that? Sounded like rock falling."

The slab on which they stood settled visibly.

"An earthquake, perhaps?" said the Professor.

"It appeared to me that the stone moved be-

neath my feet."

They both looked down.

"This is most interesting," Dr. Tresselt said,

thoughtfully. "We appear to be standing on a

mass of loose rubble. I have a feeling that our

combined weights are unsettling it."

"I think, my dear Alvin," said the Professor,

"that we had better get off as quickly as—

"

And suddenly, everything happened at once.

Irene uttered a scream. The two men were only

a short distance from the shelf on which the

young people were standing, and they both gave

tremendous leaps. Joe grabbed Dr. Tresselt's

arm, and Danny caught the Professor. They

were safe. But those jumps had given the slab

a jolt which was too much for the loose rocks be-

neath. With a slow, ponderous crash, the whole

mass collapsed.

69

CHAPTER NINE

A Loss and a Decision

The five stood huddled together, gazing at each

other in dismay. Then they turned their lamps

into the gap at their feet. Dust rose like smoke

through the beams of light, but they could see

clearly enough what had happened. The stones

had sunk carrying the slab of rock with them, and

it now lay wedged across the sloping walls of the

chasm a good ten feet below.

"I think," said the Professor, "that that's as

far as it will fall. If we have some rope with us

we can get down to it."

"We've got lots of rope," Danny said. "But

I wonder if it's really firm. It would be awful

to get down on it and have it slide another fifty

feet, or break in half."

"There's also the problem of getting up the

other side," said Dr. Tresselt, solemnly.

Professor Bullfinch took out his pipe and lit

it with a preoccupied air. "It looks as though wehave a serious problem on our hands. In the

first place, how much rope have we actually got?"

70

"I have fifty feet of clothesline in my pack,"

Danny answered. "Irene has some, too."

"Only about ten feet," she said. "It's all mymother could spare."

"Hmm. That should be enough." The Pro-

fessor blew out a plume of smoke. "I think the

four of you could hold me on that line and lower

me to the slab. If it seemed secure, one of the

boys could come down and stand on my shoul-

ders—Joe, I imagine, would be a bit lighter than

Danny. He could get up to the top of the other

side. There are several stalagmites over there

to which a piece of line could be fastened, and

we could all climb up."

"There's one thing against that, Euclid," said

Dr. Tresselt. "It's a dangerous stunt, balancing

a boy on your shoulders, on a narrow slab of rock

like that."

"There's another thing against it," Joe put in.

"Me. I'm against it."

"I'll do it. Professor," Danny said. "And I'll

bet I don't weigh much more than Joe does.

He's just stretched out more than I am."

"We may have to do that as a last resort," said

the Professor. "However, there is another alter-

native. We can go on through this tunnel in the

hope of finding another way out. I can think of

several caves—Howe Caverns, in New York

71

State, for example—which have two or more en-

trances. It is just possible that there's a way out

on the other side of Sugarloaf."

"It's a slim chance," said Dr. Tresselt. "How-

ever, I think we ought to take it. If we can't

find another way, we can always return here and

try your acrobatic method."

"Very well. Then let's get started," the Pro-

fessor said. "How are the lights? Still holding

up?"

"Still bright enough," said Dr. Tresselt. "Agood thing we didn't drop ours when we had to

jump."

They bent to pick up their things. Suddenly,

Joe let out a howl.

"Great heavens!" exclaimed the Professor.

"What's the matter?"

"Are you hurt?" said Irene.

Joe was flashing his light here and there, and

making so much noise that he didn't hear them.

Dr. Tresselt seized his arm.

"Stop!" shouted the geologist. "Be quiet!

Now, for goodness' sake, tell us what's wrong

so that we can help you."

"You can't help me," groaned Joe. "Nobody

can help me."

Danny patted his friend on the back. "Tell

us, Joe," he begged. "I'm sure the Professor and

72

Dr. Tresselt between them can do something."

"They've already done it," Joe said, growing

somewhat quieter.

"What?"

"When they jumped, I caught Dr. Tresselt's

arms and we staggered backward. You and the

Professor fell against us. Somebody's foot must

have hit my knapsack and knocked it off the

ledge. It's gone!"

There was silence for a moment. Then Irene

said, "Oh, Joel All that yelling—? You can al-

ways get another knapsack. You can have mine

if it will make you feel better."

"What good is yours?" said Joe. "All the food

was in mine—all except a couple of chocolate

bars I've got in my pocket. We'll starve I"

The Professor burst into laughter. Dr. Tres-

selt said, "I don't really think we'll be here long

enough to starve, Joe. I'm sure we can either

find another way out, or get back somehow across

this gap."

"You don't know me," Joe said, tragically. "I

can starve in a minute."

"Buck up, my lad," said Professor Bullfinch,

cheerfully. "Your hunger will give us a further

reason for escaping. Meanwhile, put up with it

as best you can."

Joe nodded. After a moment's thought, he

73

took out his notebook and wrote, " 'Weak, totter-

ing, and famished though I was, I divided the

last of my food with my friends, and we pressed

on.' There. A noble act like that makes me feel

much better." He pulled two candy bars from

his pocket and offered them around.

They broke off bits of the chocolate and

munched them. Feeling much refreshed,

Danny and Irene slung their knapsacks on their

backs, and Joe offered to carry the C-ray for a

while. Then Dr. Tresselt, holding his lantern

high, stepped forward.

74

CHAPTER TEN

Danny in the Dark

The shelf ended in a wall of stone, covered

with folds and ripples made by the minerals

washing down from the earth above. It looked

like a curtain, but shone glassily where their

lights struck it. A wide opening led them into

another tunnel, and they began to descend again.

Spikes and spires rose about them, and stalactites

of all sizes hung from above.

Danny said, "We ought to name these places

as we go through them. Look there—those sta-

lactites are like a row of teeth. We could call

this the Dragon's Mouth."

"Yes, what we really need is to make a map,"

Irene suggested.

"What for?" said Joe. "If we ever get out of

here, I won't need a map because I won't come

back."

"Why, Joe, this is a marvelous discovery,"

Irene said. "These caves might become famous,

like Luray Caverns or Mammoth Cave. People

would come from all over America to see them."

75

"Gee, I never thought of that," said Joe, en-

thusiastically. "Why, we could make a fortune,

I can see it now: Pearson, Dunn, Miller, Bull-

finch & Tresselt Caverns, admission one dol-

lar. Maybe we could just call them the Pearson

Caverns, for short. Oh, boy I First, I'll buy a

gold-plated bicycle—

"

"Hold on a minute, Joe," chuckled the Profes-

sor. "Don't get too excited. In the first place,

we don't own this land. It belongs to the town.

However, I should think Irene is right in one

way. These caves are a real discovery. Midston

should be grateful to you three. You might even

get jobs as guides, if the caves should ever be

opened to the public. However, before that

happens, we have to find our way out of here."

"Yes, I almost forgot about that," sighed Joe.

"Why did you have to remind me?"

"Have you been dropping the radioactive ma-

terial as we go, Danny?" Irene asked.

"No, not yet," said Dan, climbing around a

stalagmite that rose like a tree in the center of

the tunnel. "So far, there's been no chance of

missing the way back. But it looks as though

I'll be using it soon."

"Why?"

"The way divides up ahead. I can see another

tunnel leading off to the left."

76

"Quite right," said Dr. Tresselt. "Now, the

question is, which one do we take?"

They drew together, staring at the fork. The

Professor said, "Perhaps we ought to send a scout

a little way down to see what it's like."

"I'll go," Danny cried eagerly, and without

waiting for permission he darted ahead into the

branching tunnel.

"Just a minute—

" the Professor began, but

the boy was already out of sight around an angle

of rock.

This tunnel twisted back and forth, and it was

very narrow, so narrow that Dan could reach out

and touch the walls on either hand. They were

different, too, from those in the passage he had

just left: they were streaked here and there with

dark red, as ominous as blood. There were no

stone icicles or pillars, only the flat floor under-

foot, and the cramped, winding walls that came

together high above.

Danny began to feel a trifle uneasy. He had

started off full of excitement, but now that he

was alone he was very conscious of the silence. It

was absolute silence, in which there was only the

soft padding of his footsteps. When he stopped

for a moment, he was surprised to hear a dull

pounding. It took him a few seconds to realize

that it was the beating of his own pulses. He77

whistled a few notes, but they died away amongst

the solid stone, and he soon gave it up; it made

him feel even lonelier. He went on and the

walls began to close together. The passageway

grew narrower still and at last there was only a

small crack, just barely wide enough for him to

squeeze through.

He stood still. The thumping of his heart

shook his whole body, and his flashlight trembled

in his hand. Maybe I'd better turn back right

now, he thought.

Then he pulled himself together. Nol he said

to himself. I volunteered for this, and shoved

on in here even though the Professor tried to stop

me. I'll go on until I have to stop.

He took a long breath and went on. Soon,

he had to turn sideways, and the rough stone

scraped his back and chest, bunching up the

leather jacket he was wearing. He could feel it

pull and scrape on projections of stone.

All at once, there was nothing under his right

foot.

Nothing! Even as the thought flashed

through his mind, his foot went down into

empty air and he threw out his right hand to

try to find some support. His flashlight went

whirling away, and vanished into a huge black

space, and in the same instant he realized that

he was not going to fall. He was wedged tightly

78

between the rocks by the folds of his jacket, and

this held him securely in place.

He was too frightened even to yell. He just

stood still, clinging to a point of stone with his

left hand, his breath caught in his throat. At

the same time, his mind was busy counting: one,

two, three, four, five . . . and then he heard the

faint clatter as his flashlight hit bottom some-

where far below.

He gulped. Then he calmed himself a little

and got his right foot back on the firm rock. Heinched himself away from that dreadful edge

which he could no longer see. He was in abso-

lute pitch darkness, a kind of darkness he had

never experienced before, not even when he had

once been shut in a closet by accident. This was

a blackness which had never known any light,

and he felt as if he were being crushed by it.

Now, he was thankful that the walls were so

close together. He put a hand on either wall

and walked back the way he had come, trying

not to give way to panic and break into a run.

He kept telling himself that he would see his

friends any minute. In spite of the coolness of

the air he was drenched with sweat and had to

keep wiping his eyes on his sleeve.

The passage seemed to go on forever. But

just as he was beginning to feel that he really

couldn't bear it any longer and would have to

79

start yelling for help, he saw a pale glow ahead.

It grew brighter, and then he could hear the

happy sound of voices.

He came out into the light of his friends' lan-

terns and stood there blinking.

"Well, it's about time," said the Professor,

speaking in what was, for him, a rather severe

tone. "Please, Danny, don't ever rush off like

that again. You must learn to control your im-

pulses, at least while we're still in these caves."

Danny tried to get his breathing back to nor-

mal again. At length he said, "I'm—I'm sorry.

I know it was dopy. I won't do it again."

"What about the tunnel?" asked Dr. Tresselt.

"Any good?"

Danny mopped his face. "No good to any-

body," he said, with a shudder. "Just no good at

all."

"We were about to follow you," said the Pro-

fessor. "Good heavens! Did you know that the

back of your jacket is torn?" He looked more

closely at the boy. "And you're as white as a

sheet. Danny! What happened? What did

you find?"

"Nothing."

"Nothing?"

"That's right. The passage goes on until it

turns into a lemon squeezer, and then it becomes

80

—nothing. Just air. Listen, Professor Bull-

finch, what's the formula for a free-falling

body?"

The Professor, with a slightly puzzled air, re-

plied, "s=y2gt^"

Danny did a quick calculation in his head.

"It took my flashlight five seconds to fall," he

said. "So that pit is about four hundred feet

deep. All I have to say," he finished, with a

shudder, "is that it's a good thing I was wearing

this heavy leather jacket and not a light, thin

sweater."

He told them the whole story, and when he

was done Professor Bullfinch said, gravely, "A

very lucky escape, my boy. That settles it; from

now on we must all keep together. There must

be no dashing off alone. Danny, I've told you

several times that you must learn not to be so

headstrong. A scientist must consider every step

carefully before he moves, and if you expect to

live to become a scientist—

"

"Don't worry. Professor," Danny said. "I'm

not going to forget that moment in a hurry.

When my foot just went into empty air—ughl"

"Good." Professor Bullfinch smiled affec-

tionately at the boy. "Now, let's go on. I'll

walk in front, this time."

81

CHAPTER ELEVEN

The Glittering Cave

Danny carefully laid a trail of thorium nitrate

crystals so that he would be able to find the right

path with his Geiger counter on the way back.

As they were waiting, Dr. Tresselt tapped Pro-

fessor Bullfinch on the arm.

"Euclid," he said, "before we go on, I'd like

to take a look at those reddish streaks Danny de-

scribed, on the walls of this branch tunnel."

The Professor looked doubtful. "Do you

think it's wise?"

"I'll only go a little way in. As a matter of

fact," said Dr. Tresselt, "why don't you come

with me, and bring that Cray? This might be

a good time to try it. I have an idea about those

streaks, and your device, if it works, might be

helpful."

They entered the branch tunnel, and when

they had gone round the first sharp angle of the

rock, Dr. Tresselt pulled out his hammer and a

small chisel. Professor Bullfinch held the light

up for him, and the geologist examined the wall

82

carefully. Then he chipped out a few pieces of

the red material.

"I think this may be clay," he said. "Or per-

haps mud, with a high percentage of iron oxides.

It's embedded in the limestone. What does that

suggest to you?"

Joe, who was peering over the Professor's

shoulder, said, "Mud pies."

The Professor snorted. "Not exactly. Theriver?"

"Just so," Dr. Tresselt agreed. "It looks very

much as though there had once been another

stream running through here, carrying mud in

with it. Or. . .." He paused, tapping his ham-

mer pensively against the wall.

"Or?"

83

"I wonder if mud could have been washed in

by the flooding of a river outside? Then, when

the water subsided, the mud would remain and

petrify. Much later, another stream might have

risen in the mountain and begun to make its way

through here, cutting away the solid mud and

leaving these traces. Then that stream, too,

vanished in its turn."

The Professor nodded. "I see. Let's try the

C-ray. It may show us some fossils in the mud."

It was difficult to work in that narrow space,

but they got the machine braced on top of one

of the knapsacks and the Professor turned it on.

It hummed faintly, and the screen lit up. They

saw a blurred tangle of vague shadows against

the glow.

"Not very clear, is it?" said Dr. Tresselt.

The Professor turned a knob. Nothing hap-

pened. He began fussing with dials and snap-

ping switches on and off, muttering to himself

as he did so. Still, they could see nothing but

those shadowy shapes, like the trailing edges of

clouds.

"Too bad," said Dr. Tresselt. "But I was

afraid it wouldn't operate properly on stone."

Professor Bullfinch sighed, and snapped off

the C-ray.

"Well," said Irene, as she picked up her pack

84

again, "it's a good thing there isn't any fossil Joe

inside that wall, stealing a stone chicken leg."

"Even a stone chicken leg wouldn't be so

bad," Joe grumbled.

Dr. Tresselt flashed his light down the tunnel.

"I'd like to follow this to the end," he said, wist-

fully.

"Not today, Alvin," said the Professor. "In

the first place, if Dan was right you couldn't

squeeze through the last part of it."

"And a good thing, too," said Danny, with a

shiver.

"But it's important," said the geologist.

"It's more important for us to find a way out,"

the Professor said.

"Mm. Yes. Well, I'm pretty sure that water

came in here from another source," said Dr.

Tresselt. "Not from the river we followed. So

if we keep going, we have a good chance of find-

ing another way out—the place where that water

entered."

They returned to the main tunnel. Joe took

the Cray and let Danny carry his flashlight. Off

they went again, with the Professor in the lead.

The tunnel began to grow smaller. The roof

lowered, the walls drew in, and they had to go

single-file once more. The Professor picked his

way carefully, climbing over rough places and

85

worming his way around and over bulges in the

rocky walls. Suddenly, he stopped short.

Danny, who was behind him, said, "What's

the matter. Professor?"

"Nothing's the matter," he answered. "But

this is well worth seeing."

"What is?"

"Spectacular," the Professor went on, without

budging. "Truly beautiful."

"Professor Bullfinch!" Danny yelled.

"Eh? What's the matter?"

"You keep talking about how beautiful some-

thing is, but we can't see a thing unless you move

out of the way."

"Oh, sorry," laughed the Professor, and

stepped forward. The others followed him at

once. They found themselves standing in an

immense cavern, far larger than anything they

had yet seen.

They saw at once why the Professor had ex-

claimed as he did. Their lamps seemed to flash

from countless jewels, as they played them about

the walls. From the high arched ceiling hung

thick stalactites with rippled surfaces, some of

them dark red, or brown, or jade green. Weird

shapes rose all about them: rocks banded with

many colors, worn and cut by water that had

flowed through this chamber and carved it out

86

countless millions of years before. Everywhere

were crystals which sparkled like snow in the

beams of the lights, or polished surfaces beaded

with moisture, and as they stood silently gazing

about them they heard the steady dripping of

water from a dozen places, water that would

slowly form more stalactites and stalagmites.

"Jumping catfish!" breathed Joe at last.

"I agree with you," said the Professor.

"There doesn't seem to be much else to say."

87

CHAPTER TWELVE

^^The Whole Cave Is

Radioactive!''

The five explorers advanced into the center of

the cave. Here, the floor rose in a series of flat

shelves, or rather, steps, to a kind of platform

some six or seven feet high. Above this hung

three huge stalactites, almost touching the top

of it. Dr. Tresselt climbed up on the platform

and placed his light behind one of the stalactites.

They could see the light shining right through

the translucent stone as if it were some kind of

thick glass, now yellow, then as he moved the

lamp, a faint rose color.

"Listen," he said, and tapped the stalactite

with his hammer, gently. A deep-toned note

boomed through the cavern, like a great bell.

"Gee, what a church this would make," Joe

said, admiringly. "It's got everything—even an

altar and a bell."

They began wandering about the cavern, feast-

ing their eyes on its wonders. They found a

rock that looked like the face of an old witch, and

88

another that had been worn into the shape of a

roaring lion. They found, too, that there were

a number of other tunnels leading out of this

cave as if it were some central hall in an ancient

castle, with all its passageways running off in

every direction. They were of all sizes, some

barely large enough for a man to creep into,

some larger than the front door of a house.

"Let's sit down and rest for a bit," the Profes-

sor said, after some moments.

They made themselves as comfortable as they

could on the steps of what they called the

"Altar," and Joe pulled out a bag of peanuts.

"I found these when we were looking through

our pockets a while ago," he said, proudly.

"Just let me count them. . .."

"A peanut counter!" giggled Irene. "Almost

as good as a Geiger counter."

"Better," said Joe. "We've got to ration our-

selves, though. Let's see, five apiece and two

left over. Hmm. Professor Bullfinch, what's the

formula for dividing two peanuts among five peo-

ple?"

"Much too complicated, Joe," said the Profes-

sor soberly. "Why don't you simply split them

in half. Each of you young people take one half,

and Dr. Tresselt and I will divide the remaining

half between us."

89

The five explorers advanced into the cave.

Dr. Tresselt nodded. "We aren't quite as

hungry as you are, I'm sure."

They ate their peanuts, with solemn and quiet

pleasure.

"How quiet it is," Danny said, digging in his

knapsack for the canteen full of water he had

brought. "You don't realize how scary it is,

having a whole mountain on top of you, until

you're in the dark as I was in that tunnel, or

when you begin hearing the silence."

"I didn't know you could hear silence," said

Irene.

"Then just listen."

They sat still, and Danny added, "Put out the

flashlights for a minute."

In the dark, they understood what he meant.

All the familiar noises of the upper world were

gone: the wind, the rustle of branches or leaves,

the chirping of birds, the sounds of automobiles

and doors slamming, and people laughing.

There was nothing but the faint tinkle of drop-

lets of water, each drop like a distant musical

chime, and each one pursued by tiny echoes.

Then, after such a note had sounded there would

be a long and empty quiet in which they could

hear their own breathing and the steady beating

of their hearts. They found themselves strain-

ing their eyes to see something—anything—the

92

slightest sign of light, but they could not even

tell the difference between opening their eyes

and shutting them.

Irene burst out suddenly, "Put on the lightsl"

Danny let out his breath with a whoosh.

They all snapped on their lamps, and as the

welcome light flooded the chamber, he said, "It's

—it's like being buried alive."

"Don't let's try that experiment again," Irene

said, with a shiver. "I just hope we get out of

here before our flashlights give out."

"Yes," said the Professor, "perhaps we'd bet-

ter start back. There are so many ways out of

this cave that it would be hopeless for us to try

to guess which one will take us back to the sur-

face. At least, we know the way back, and when

we come to the stone bridge we'll just have to

figure out a way to get across it. I still think wecan manage with our ropes."

"All right," said Dr. Tresselt. "Now, which

way did we come?"

"Don't worry about that," Danny grinned.

"I remembered to drop the thorium nitrate at

the entrance. Just let me unpack the Geiger

counter."

He got it out and put the earphones over his

ears. In his left hand he carried the box which

contained the power source and amplifier, and

93

in his right the tube which looked like a micro-

phone but which was the counter itself.

"Let's see," he mused. "I think it was that

one, where that shiny dark patch of stone is."

He went to the opening he had indicated, and

held the counter close to the ground, moving it

to and fro.

"Yep I" he said. "This is it. I can hear the

clicking."

He led the way into the tunnel. But they had

not gone twenty yards before they came up

against a blank wall, deeply scored as if water

had churned round and round against it. At the

bottom was a dark hole, much too small for them

to get through.

"We certainly didn't come up that hole," the

Professor observed.

"I must have made a mistake," Danny said.

"I guess I was wrong about the clicks."

They retraced their steps, and after searching

about for a little while, Danny stopped at an-

other tunnel. "This is the one," he said. "I

remember leaning against the pointed rock.

Anyway, I think I remember. . .."

He pressed the switch, and passed the counter

back and forth. Then he took off the earphones

and held them out. They could all hear the

rapid, tiny clicking of the device.

94

"That's it for sure," said Joe. "Come on, let's

get going. This place is giving me the creeps.

I'd rather face the stone bridge and know that

I was on my way back up to the surface, for

sure."

They entered the second tunnel. But in a

very short time, its walls closed in and then it

came to an end.

"This isn't the one either," said Dr. Tresselt.

They returned to the main chamber, and

stared at each other, somewhat fearfully.

"I don't understand," Irene said. "We all

heard the clicking. What was it, if it wasn't the

radioactive material Danny dropped?"

"Maybe something's wrong with the Geiger

counter," said Joe.

"No, I'm sure there's nothing wrong with it,

or it wouldn't make any sound at all," said

Danny. "Gosh! Maybe—maybe the whole

cave is radioactive? Uranium! That's it!

Maybe the place is full of uranium."

Dr. Tresselt shook his head. "I find that dif-

ficult to believe," he said. "There have been no

traces of pitchblende or any such substance. Of

course, there are radioactive substances beside

uranium which might activate the counter."

Professor Bullfinch nodded. "It is just pos-

sible that the cave is mildly radioactive," he said.

95

"What'll we do, then?" Joe demanded.

"There are lots of tunnels. Even if the next one

we try doesn't end in a blank wall, how are wegoing to tell if it's the right one? We can't just

wander around for hours and hours and hours.

... Or can we?"

Nobody answered him. He looked from one

to the other. Then he said, "We're stuck,

aren't we? Trapped inside a whole mountain

of rock. Locked up—and we can't find the

key!"

96

CHAPTER THIRTEEN

A Disappearance

With his usual composure and cheeriness, the

Professor took command. "Let's all go back to

the 'Altar' and sit down for a moment," he said.

"Sit down? What good will that do?" Joe

asked, glumly.

"It will allow us to calm ourselves," said the

Professor. "You can't think clearly if you're

worried or upset."

He led them to the platform and they sat down

on the steps. The Professor pulled out his old

pipe and lit it, and after a puff or two, said, "I'll

admit the situation looks bad. But I don't think

we need give way to absolute despair. It isn't

as if there were an infinite number of ways out

of this place. There are no more than a dozen

or so, and some of those we can cross off because

they're smaller than the way we entered by."

Irene said, "Then all we have to do is try one

after the other, and sooner or later we'll hit the

right one."

"Sure, that's all," Joe said. "A mere nothing.

Suppose it takes two or three days? We could

97

die of hunger or thirst, or our lights could wear

out. We wouldn't get far in the dark."

"Exactly!" said Professor Bullfinch. "Joe,

you've hit it right on the head."

"Gee, really?" Joe said. "Good for me.

What'd I say?"

"We must be careful not to waste our lights.

Therefore, I suggest that we use only one at a

time and save the others. I don't think we'll be

here for days. But the sooner we start off, the

better. I'll go first, with one of the big battery

lamps. You youngsters follow me, and keep

your lights off. Alvin, you bring up the rear."

Dr. Tresselt said nothing. He appeared to

be deep in thought.

"Alvinl" repeated Professor Bullfinch. "Did

you hear me?"

"Er—yes. Yes, yes, yes. Splendid idea. I'm

all for it," said Dr. Tresselt, with a start.

The Professor got up, and went up the steps

to stand beside the three big stalactites hanging

above the "Altar." "Now, then, let me think a

moment," he said. "As I recall it, when wewalked up to this stone platform, we saw the

three stalactites lined up, one behind the other.

If I'm right, the tunnel we want should lie either

in that direction, or directly opposite."

He pointed, and then climbed down and

98

walked resolutely forward. The beam of his

lantern picked out a dark opening between two

long ribs of fluted stone. On either side of it

other, smaller, holes appeared, but the one in

the center seemed to be about the right size.

"It doesn't look absolutely familiar," said

the Professor, "but let's chance it. Don't forget,

even if it isn't the way by which we came, there's

always the possibility that it may be another way

out to the surface."

He strode forward. The passage, at first just

large enough to permit him to walk upright,

widened and grew larger. The Professor moved

steadily onward. But suddenly, his light shone

out into empty space. The floor of the passage

ended, and he found that he was standing on the

lip of a sheer drop, a kind of miniature cliff,

overlooking another large cavern.

"Trouble again," said Joe.

Danny got down on his hands and knees and

peered over the brink. "Shine your light down.

Professor Bullfinch," he said. "Look, there's a

crack running at a slant down the face of this

cliff. It's wide enough to stand on and get your

toes into. It goes down—oh, maybe for twenty

feet or so, and then I can see gravel, a big bank

of it, fanning down in a slope. It wouldn't be

hard to get to the bottom."

99

"Yeah, but what for?" Joe asked. "What's

down there?"

"I don't know what's down there, Joe," said

the Professor, "but there's something up here."

He raised one hand, turning it about. "There's

a definite current of air here. I can feel it.

That may mean an opening—air blowing in

from outside."

"Then let's investigate it," said Danny, ea-

gerly.

"I mean to," the Professor replied. "I'll go

down first."

"Oh," said Danny.

The Professor took Danny's rope and tied it

firmly to a short but thick stalagmite a little way

back from the edge. He let it dangle over the

drop and followed it down with the beam of his

lamp.

"Plenty of line," he said. "You're right, Dan.

I don't think it's more than twenty feet to that

gravel, and from there I should have no diffi-

culty."

He sat on the edge and put his toes into the

shelving crack. "We can break our rule for this

once, and use all the lights," he said. "I'll hold

the rope as I go. If, when I get to the bottom,

it looks promising, I'll call and you can let down

100

the packs and the Cray, and then come down

yourselves. Otherwise, I'll simply climb back."

He winked. "Keep your chins up," he

smiled, and started down.

Danny watched from above, holding the beam

of his flashlight steady on the Professor's bald

head. They saw him reach the gravel and, still

holding the rope, make his way downward, slid-

ing and staggering. They could hear the rattle

of stones. Then the rope went slack, and they

guessed he had come to the end of it and let it

go. They saw his light flashing from side to side,

and suddenly it vanished.

Before they could speak, it went on again. It

shone steadily in one place for a few minutes,

and then it began jerking and bobbing in a cu-

rious fashion. They heard the Professor call

out. Both the distance and the echoes made it

impossible to hear what he was saying.

"But that doesn't matter," Danny said. "Hetold us he'd yell if it was safe. Come on, let's

send down the knapsacks."

They hauled up the rope and quickly tied

their packs and the C-ray to it. Slowly and care-

fully, they let their burden down until they

could see it land on the top of the gravel slide.

They waited for the Professor to come up and

101

untie it. But his light remained where it was,

and once again they heard him shout something

they couldn't understand.

"I'm going down," Danny said, abruptly.

"Oh, Dan, do you think you should?" said

Irene, gripping his arm.

"There's something wrong. I've got to go."

He swung himself over the edge and without

bothering about the rope edged quickly along

the crack, clinging to the rock face with his fin-

gers. It was rough enough to offer him plenty

of handholds. He reached the gravel without

trouble, and started down it toward the Profes-

sor's light, which he could see near the bottom.

"Professor Bullfinchl" he called.

"I'm here," came the answer. "But be care-

ful. Try not to start any of the stones rolling if

you can help it."

Picking his way downward, Danny found the

Professor seated on a round, smooth boulder

with his lamp at his feet. He had one shoe off,

and was binding up his ankle with a blood-

stained handkerchief.

"I'm afraid it's sprained," he said, apologet-

ically.

Danny fell on his knees. "Let me look," he

said.

There was a long, but fortunately rather shal-

102

low cut on the Professor's leg. His ankle was

bruised and already quite swollen.

"The gravel began slipping under me," the

Professor explained. "I lost my balance, and

then I caught my foot between two large stones."

"Can you walk?" Danny asked.

"Not very well, I'm afraid. The worst of it

is, I'm sure I can't climb back up that cliff."

Danny went to the top of the gravel pile and

called to the others. "Come on down."

"What's the matter?" Irene shouted.

"It's the Professor. He's hurt."

As they started down the cliff, Danny untied

the C-ray and the knapsacks and carried them to

where the Professor sat. He began rummaging

in Irene's pack for the first-aid kit. "Be care-

ful," he called, as Irene and Joe came down the

slope. "We don't want any more sprained

ankles."

Irene, who was an expert in first aid, set to

work at once washing the Professor's wound with

the rest of the water from the canteen. She

dressed the sides of the cut with Mercurochrome,

and then taped up his ankle. "How's that?"

she said.

"It feels better already," said the Professor.

Joe, watching with his hands shoved deep in

his pockets, said, "You know, this could mean

103

trouble. How are we going to get him back up

that cliff?"

The Professor glanced up mildly. "There's

one other small point which could mean trou-

ble," he said.

"This could mean trouble."

"What?" said Danny, who held the light for

Irene, as she repacked her kit.

"Well . . . where, exactly, is Dr. Tresselt?"

The three young people exchanged startled

and horrified glances.

"Great jumping gleepers!" said Danny, at

last. "I—I forgot all about him. I guess I

thought he was following us."

"So did I," said Irene. "And it was dark,

too. . . . Now that you mention it, I don't know

when I last saw him."

They stared at each other, and Joe let out a

long groan of despair.

105

CHAPTER FOURTEEN

A Charm for Engineering

"Weill" said Professor Bullfinch. "This is a

fine mess."

"It's a mess all right," Joe said, rolling up his

eyes. "But what's fine about it?"

"Maybe he's back in the tunnel a little way,"

Danny suggested. "He might have stopped to

look at something. Let's yell for him."

All together, they shouted at the tops of their

voices: ''Doctor Tresselt! DOCTOR TRES-SELT!"

There was no reply.

The young people sank to the ground, and

even Professor Bullfinch looked a little discour-

aged. "I should have thought of this," he said.

"It would have been wiser, perhaps, to send him

in the lead where we could keep an eye on him."

"But where could he be. Professor?" Irene

said.

"I should guess," the Professor answered,

"that he saw something which caught his atten-

tion back in the glittering cavern, and that he

106

is either still there, or has taken one of the other

tunnels. There's no way of telling. WhenAlvin becomes absorbed in his work he forgets

everything else, as you know."

He drew out his faithful pipe and began

slowly filling it. "Maybe this will help methink," he said. "Cheer up, friends. We're

not finished yet. Don't look so downhearted,

Danny. You should know that to a scientist

every problem has a solution. It's just a matter

of time before we find the answer to this one."

"I wasn't looking sad because of that," Danny

said. "I was just thinking—well—that this

whole thing is my fault."

"Really? That's very interesting. How do

you make that out?"

"I found the cave, didn't I? And I was the

one who suggested that we make the trip. Andif I had only thought of a simpler way of mark-

ing the trail instead of trying to be so scien-

tific— ! How was I to know that the whole cav-

ern would be radioactive? And I shouldn't

have crossed that stone bridge, either. Wemight still be safe on the other side."

The Professor drew at his pipe with enjoy-

ment, and puffed out half a dozen smoke rings.

He watched them drift up a little way and then

dissolve. "Dear me," he said, "you have cer-

107

tainly made out a dismal case against yourself.

However, Dr. Tresselt was as eager to go as you

were, and it was I who agreed to the expedi-

tion. I'm afraid your mother was right about

us after all. I've hurt my ankle, and Dr. Tres-

selt is—well—heaven knows where.

"As for the stone bridge, you certainly didn't

make it collapse. Alvin and I should have

known better than to go across it together. It

was our combined weight that made it fall; wewere so deep in our discussion that we weren't

thinking.

"It's true, the Geiger counter was your idea.

Actually, not a bad one, either. As you say, howwere you to guess that something would go

wrong?"

He grinned at Danny, his eyes twinkling be-

hind his glasses. "My dear boy, there's no doubt

you are headstrong, and you often act without

thinking of the consequences. But you mustn't

try to take too much blame. Leave some of it

for other people 1"

He tamped the tobacco down into his pipe

with a calloused thumb. "There's a good basic

principle I always follow," he went on. "Whenyou can't think of anything to do, just relax. I

propose we do just that. I'll rest my ankle so

that perhaps I can walk on it a bit, and if we just

108

sit here for a while Alvin may find us of his ownaccord."

"That's true," Irene said. "He may be in the

glittering cave, and when he realizes he's alone

he'll follow us."

Joe pulled out his notebook and began scrib-

bling. Danny sat down next to the Cray and

gazed at it mournfully, running his finger along

its smooth metal case.

Irene said, "Professor Bullfinch is right, Dan.

Stop brooding! I don't blame you, and neither

do the others."

"No ... it isn't that," he replied, with a sigh.

"I'm all mixed up, inside. I keep thinking

about so many different ideas—getting out of

here, and finding Dr. Tresselt, and the Profes-

sor's ankle—

"

He frowned. "There's something else, too.

I keep having the feeling that there's something

in the back of my mind, something I've forgot-

ten. If I could only remember what it is, I think

we'd know what to do. Something important,

too. . .."

"Well, I hope you remember it," Irene said.

She got up and wandered aside a little way, flash-

ing her light on the ground.

Joe cleared his throat. "I don't suppose you'd

like to hear a poem I just wrote, would you?"

109

"A good idea, Joe," said the Professor. "It

will make us all feel better, I'm sure. Go ahead."

Joe stuck his pencil behind his ear, and began

to read:

"A cave man sat in his cave of stone.

Picking his teeth with an old steak bone.

He felt very brave

While in his cave.

Though he didn't have lights or a telephone.

But all at once he heard a roar.

And a sabertooth tiger was at his door!

The poor old mole

Was in a hole,

And the tiger would have his hide, he swore.

But just as the tiger wrinkled his snout.

The cave man jumped to his feet with a shout.

He grabbed the back wall

And gave it a haul.

And turned his cave right inside out!

Then he was out, and the tiger in.

So he rolled up a rock with a cheerful grin;

He blocked the way

For a week and a day,

And now he's wearing a tiger skin."

He bowed modestly as the- others clapped

their hands. "That's marvelous, Joe-," Irene ex-

claimed. "How do you do it?"

"Oh, I don't know." Joe shrugged. "I just

110

put the pencil on the paper, cross my eyes, and

out comes a poem. As far as that goes, I've al-

ways wondered how you and Danny manage so

easily with arithmetic. That's my worst sub-

ject."

"Well, I'm delighted we have you with us,

Joe," chuckled the Professor. "Poetry and sci-

ence go very well together."

Danny bent over the Cray once again. "If

only we could get this thing working," he mut-

tered, shining the flashlight on the machine.

"What good would that do?" said Joe. "Do

you think Dr. Tresselt has turned into a fossil?"

"I can't understand—

" the Professor began.

Danny interrupted him with a yelp. "Pro-

fessor Bullfinch! I think I know what's wrong."

"Really? What is it?" asked the Professor,

eagerly.

"It's the knob that controls the focus," said

Danny. "Look, when you turn it, it just moves

loosely. See? It was held on by a little nut, or

something like that, and the nut is gone."

The Professor, supporting himself carefully

to keep his weight off his ankle, bent forward to

peer at the machine. "Yes, by George! You're

right. You have good eyes, my boy. It must

have fallen off when we took that slide into the

mud."

Ill

"Isn't there any way of fixing it?" asked Irene.

"I don't see how," said the Professor. "I

didn't bring any spare parts. Unless—perhaps

one of the boys has a replacement in his pocket?"

Danny and Joe at once turned their pockets

inside out. "We've got enough to stock a gen-

eral store," Danny sighed. "Rubber bands, pen-

cils, string, paper, stamps, knives, a watch spring,

a cog-wheel—you name it. But no nuts or bolts.

Isn't that always the way when you want some-

thing?"

"Maybe we could hold it on with chewing

gum?" Joe suggested.

"A great idea. Got any gum?"

"Um . . . no."

Danny sank back and put his chin in his hands,

plunged even deeper into gloom. The Professor

turned his pipe over and over as if it might give

him an idea. Joe began writing in his notebook,

once again, and Irene returned to her searching

about on the ground.

Suddenly, she bent and picked something up.

"Ah!" she cried. "Maybe this would do."

"What would do what?" asked Danny. "What

have you been looking for?"

"You remember, I said I wanted to get some-

thing to represent geology on my charm brace-

let," Irene said. "I've been keeping my eyes

112

open for some sort of pretty little pebble. I

thought that here, where all this gravel has piled

up, I might find something. And look—this one

is just the right size."

She held out a small, pure white stone, pol-

ished and shining, and about the size of her lit-

tlest finger nail.

"Maybe my father can drill a hole through it

so I can hang it on my bracelet," she said.

Danny had been staring at her in fascination.

"Braceletl" he said.

They all looked at him. "Are you wearing

your bracelet?" he went on, in a tense voice.

"Why, of course. Don't you remember?"

Irene shook her hand so that the charms jingled

together.

"Come here. Let me see it."

So excited was his tone that Irene came to him

without another word and held out her wrist.

"Engineering!" Danny said. "I thought so."

"Engi—?" Irene began.

"A small nut and bolt," Danny interrupted.

"That's what you used to represent engineer-

ing. Just what we need to fix the Cray. The

only question is, is the nut the right size? Take

it off the bracelet, Irene."

She did so, and Danny bent over the machine

with it while the others turned their lights on

113

him, and watched. He twisted the nut on the

threaded rod with fingers that trembled slightly.

"I can just—force it—on," he panted. "I

think that will hold it, though."

He straightened up. "Can I try the machine,

now, Professor?"

"Why, of course, Dan," said Professor Bull-

finch. "I hope it will work, but I don't exactly

see how this makes any difference to us."

"It does, though! " Danny snapped the switch,

and as the screen grew bright, looked up toward

the dark entrance through which they had come,

high above them. "This may help us locate Dr.

Tresselt."

He frowned. "Let's just try it on that far

wall," he said, "and see whether it's working."

He pointed the nozzle of the C-ray at the wall

and began turning the knob which regulated the

distance of the ray and brought objects into fo-

cus. A web of shadows grew on the screen.

Slowly, their outlines became clearer, sharpened

into long streaks, and then at one comer of the

screen they saw a small object come into focus.

It looked something like a scallop shell: they

could see faint, fluted markings like outspread

wings on each side of a central ridge.

"A brachiopod," exclaimed the Professor.

"Clearly, a primitive brachiopod."

114

"Golly!" said Joe. "Is that good?"

"What is it, Professor?" Irene said.

"A shellfish. Something like a—well—like a

kind of clam."

"You mean somebody ate clams inside that

wall?" said Joe. "How'd he get in there?"

"That shellfish, Joe, may have lived a hundred

million years ago," said the Professor, solemnly.

The young people were stunned. "A hun-

dred million—

" Irene gasped.

Danny began turning the scanning knob.

The shellfish vanished and the streaks began to

move sideways, as the ray swept across the wall

of stone.

Suddenly Irene cried, "Stop!"

A set of slightly curved bars came into view.

On the other side of them could be seen the dis-

tant silhouette of a man, bent over and tapping

at something with a shadowy hammer.

"The clam digger!" Joe gurgled.

"No, it's not," said Danny. "It's—it's Dr.

Tresseltl"

"But look," Irene said, in a hushed voice.

"He's in a cage!"

116

CHAPTER FIFTEEN

The Creature in the Rocks

Joe's active imagination went right to work.

"Prison!" he said, his eyes wide. "There must

be a race of underground people—like the Mor-

locks in The Time Machine—people who have

never seen the sun. They must have sneaked

up on him and captured him, and now he's lan-

guishing in one of their dungeons."

Danny cocked his head, eyeing the screen of

the Cray. "Looks more to me as if he's just

calmly collecting rock samples," he said.

"He's trying to chop his way out," Joe per-

sisted.

"It's a great hypothesis, Joe," said the Pro-

fessor, "but I think Danny's more likely to be

right. What we take for bars are just some kind

of rock formation—perhaps stalagmites of a

slightly different composition than the others."

Danny had been studying the machine.

"Well, now we know where he is," he said. "Thedepth setting is on fifty feet. It's about thirty

feet from here to the wall of the cave. So he's

117

another twenty feet beyond. I'll bet it's just the

next tunnel." He jumped up. "I'm going to

see."

The Professor raised a hand and said, "Now,

don't go charging off in all directions at once."

"I won't," Danny laughed. "Anyway, this is

easy. All I have to do is follow the passage back

to the glittering cavern, and then take the next

tunnel to the right as I come out. He should be

about the same distance down that one. Joe can

come with me to see that I don't get into trouble."

"That's a good idea," Joe said. "But who's

going to keep me from getting into trouble?"

"If you boys promise to be very careful, you

may go," said the Professor. "But don't go chas-

ing off on your own explorations. Don't take

any branch tunnels. For goodness' sake, don't

you go getting lost."

"We'll be careful," said Danny. "Come on,

Joe."

Together, they climbed the gravel slope. Therope was still hanging where they had left it, and

they had no trouble getting back to the top of

the little cliff. They plunged into the tunnel,

Danny in front with the flashlight, and went as

quickly as they could until they came out once

more in the big cavern with its "Altar" and its

sparkling walls. Danny at once turned to his

118

right. There, between two thick folds of rippled

green stone was one of the smaller openings they

had noticed before.

"Too bad you can't see footprints in the rock,"

said Joe.

"Yes, but I'll bet anything this is the way he

went," Danny answered.

They entered, stooping. The floor of this

passage was uneven and jagged, and it sloped

steeply downward. It was, in fact, more like a

deep fissure than a tunnel, as if an earthquake

had moved and split the rock and opened a nar-

row way down to the depths.

"How far shall we go?" Joe asked. "Maybe

this isn't the way at all. How are we going to

tell?"

"Hard to say." Danny climbed over a sharp

knife-edge, holding the light above his head to

keep it from banging against the stone. "Can't

judge distance in this one because it isn't flat,

like the other. Let's go on for a while, and then

worry about it if nothing turns up."

But as it happened, they didn't have too far

to go. A few moments later, Joe, who had paused

to wait for Danny to climb down out of his way,

spotted a yellow glow on the walls ahead. Aninstant later, they could both hear, quite clearly, •

the clink and tap of a hammer.

119

They slid down a last sloping slab and found

themselves in a chamber whose dull gray and

brown walls were in sharp contrast to the big

cavern they had just left. Dr. Tresselt was on

his knees examining some bits of stone by the

light of his lantern, which stood on a point of

rock nearby.

"Dr. Tresseltl" said Danny. "We've found

youl"

The geologist glanced at them over his shoul-

der. "Um?" he said, in an abstracted tone.

"Were you lost?"

Danny laughed.' "No, sir. But you are."

"I am?" The geologist raised his eyebrows.

"I don't feel lost. I know where I am."

Then, slowly, as the meaning of Danny's words

penetrated, his expression changed. "Oh, dear,"

he said. "I am sorry. I assure you, I didn't mean

to wander off. But you see, I noticed those same

red streaks at the entrance to this passageway,

and I just couldn't resist investigating. The fur-

ther I went, the more clay I found. Look about

you— ! This chamber is not limestone like the

others, but was hollowed out of petrified mud.

I have found the fossils of several fresh-water

molluscs, too. See?"

He held out what looked like small, dark peb-

bles.

120

Danny said, "But where's the cage?"

"What?" said Dr. Tresselt. "What are you

talking about? You're in the cave."

"But where are the bars?"

"Why should there be bars in a cave?"

"Not cave, Dr. Tresselt," said Joe. "Cage.

C-a-g-e."

"Cage? This isn't a cage. Why do you keep

calling it one?"

"We saw it on the C-ray screen," Danny said.

"Just as plain as could be. Big curving bars,

and you were inside them."

"Well, I'm not," Dr. Tresselt said. "I'm

afraid my friend Euclid expects too much from

that invention of his. What you saw was prob-

ably a defect of some sort—something wrong

with the machine."

"There's nothing wrong with the C-ray," said

Danny, firmly. "We saw one of those fossil shell-

fish you've found, stuck in the stone. But it's

certainly very funny that there isn't anything

here that would look like bars." He flashed his

lamp all about the small chamber. "Anyway,

let's join the others. We'll have to decide what

to do, now that the Professor has hurt his ankle."

"How did that happen?" asked Dr. Tresselt,

gathering up his things.

"He slipped on some gravel and twisted his

121

leg. Maybe you'll have some idea how to get

him back up the cliff."

They hurried back up the steep passage and

were soon standing once more on the top of the

cliff. Dr. Tresselt was agile and used to climb-

ing, and he went down the sheer face like a

mountaineer. Joe followed, and then Danny

untied the rope and let it fall so that they could

use it if necessary.

Professor Bullfinch waved, as they picked their

way down the gravelly slope. "We've been ex-

pecting you," he said. "We watched you boys

find Dr. Tresselt, on the C-ray screen."

"Do you mean to say that that thing works?"

Dr. Tresselt said.

"Perfectly. How do you think we found you?

We saw you through the wall of the chamber.

By the way, what was that rock formation that

looks like a cage?"

"A cage? Danny said something about that,"

said the geologist. "There was no such forma-

tion where I was. Let me see that apparatus."

He squatted down and stared at the screen of

the C-ray. He whistled softly between his teeth,

and said, "Is there any way of moving the pic-

ture from side to side?"

"Oh, yes. We watched you as you climbed

back up the passageway. This is the scanning

122

dial. Turn this button to one side or the other."

Dr. Tresselt did so. "What about focus?" he

asked.

Professor Bullfinch showed him what to do.

For a few moments he sat absorbed, moving first

one knob, then the other. On the screen, a

strange shape grew, its outlines clear and dark.

It looked like a fan, with a large hole below it

like an eye, then a curved eagle's beak, and two

spiky horns jutting forward.

"Congratulations, Euclid!" Dr. Tresselt said,

in a voice that trembled with excitement. "Your

C-ray is more than a success. Look at that!

Doesn't it look familiar?"

The Professor stared. Then, almost in a

whisper, he said, "It does indeed. A fossil skull.

The skull of a dinosaur!"

123

CHAPTER SIXTEEN

"Light Your Pipe!"

The Professor put a finger on the fanlike shape

showing on the screen. '

'One of the Ceratopsia,

he said. "And from the three horns, I would

say it was Triceratops."

"My feeling, too," agreed Dr. Tresselt.

"And what we thought were the bars of a

cage—

"

"Were its ribs, somewhat out of focus!"

"A tri—sephera—what you said," Joe put in.

"You mean, one of those giant prehistoric liz-

ards?"

"The fossil skeleton of one, Joe," said Dr.

Tresselt. "And a fine specimen, too, I should

judge, although I can't make out all the details

from this shadow picture. You can see the long

horns and sharp beak, and the big bony shield

that swept up behind the head to protect the

neck. Watch, now, as I move the ray. You can

see the ribs, and there's part of the backbone and

the long heavy tail."

"If it wasn't in the cave with you," said the

Professor, "where was it?"

124

"I think I can answer that," Dr. Tresselt said.

"It's embedded in the wall between this cave

and that one."

"In the solid limestone?" said the Professor.

"Isn't that a little unusual?"

"It would be exceedingly unusual, if the wall

were really limestone," said Dr. Tresselt. "But

I'll explain all that later. Meanwhile, we've

got the problem of what to do with you. Can

you walk at all?"

Professor Bullfinch got carefully to his feet

and took a step or two. He winced. "It's pretty

tender," he said. "However, I think I can hob-

ble along on it."

"Hobbling won't get us very far, not along

these underground ways," said Dr. Tresselt,

thoughtfully. "If the ground were fairly level

it wouldn't be so bad, but I don't quite see howyou're going to get over that fallen stone slab,

for instance."

"Maybe we could make a stretcher out of a

jacket and two long poles," said Irene. "That's

one of the things they taught us in my first-aid

class."

"Poles? Where would we get them, in these

caves?" Dr. Tresselt asked.

"Maybe we could use long, thin stalactites,"

Danny suggested.

125

The Professor shook his head. "I think you'd

find them harder to break off than you imagine,"

he said. "In any case, I doubt that you could

carry me all the way back. No, Alvin, I'm afraid

we've got to face it. You will have to leave mehere."

Dr. Tresselt pursed up his lips in a soundless

whistle. Then he said, "Wouldn't think of it."

"But you must. You can all go back and when

you're out you can send help back for me. As

long as I have my pipe and tobacco and some

matches, and one of the flashlights, I'll be all

right."

"Well, I won't leave you, Professor," said

Irene. "I'll stay here and keep you company.

Let the boys go back."

"Alone? I don't like that idea," the Professor

said.

"And I don't want to leave you here, either,"

said Danny.

"Well, we can't send Dr. Tresselt back by him-

self," said Dr. Tresselt, with a grin. "I might

find something interesting along the way, and

get side-tracked, and forget where I was supposed

to be going."

The Professor sighed. "We're not getting

anywhere with this discussion," he said. "Some-

body has got to go. What else can we do?"

"We could try hoddering for hep," Joe said,

thickly. "Orsedupsmokesigdals." He sneezed

loudly, and, taking out his handkerchief, blew

his nose like a trumpet.

The Professor couldn't help laughing.

"Smoke signals," he said. "A very good idea,

Joe. Or we might try sending a telegram:

Trapped in cave send help love to all. I'm

afraid that wouldn't work, either."

Danny clapped his hands together, so sharply

and suddenly that they all jumped and turned

to look at him.

"Wait a minutel" he cried. "That's itl"

"Whad's id?" said Joe.

"You I" Danny exclaimed.

Joe stepped back a pace. "Now, waid a

middud—

"

"Your nose," Danny went on, excitedly.

"And smoke signals. I've got itl That's what

I've been trying to remember ever since we got

stuck down here."

Dr. Tresselt looked completely baffled.

"Nose?" he mumbled. "Smoke signals? I'm

afraid this is too deep for me."

"Danny," said the Professor, "pull yourself

together. Tell us what you mean."

Danny had been capering about madly. Nowhe stopped. "Your pipe!" he said. "Professor

—light your pipe I"

128

CHAPTER SEVENTEEN

Into the Open

The Professor gave a long sigh. "My poor boy,"

he said. "Just sit down for a minute and rest,

and try to relax."

"See if there's any water left in the canteen,"

said Dr. Tresselt, in a worried tone. "Maybe

a cold compress on his forehead—

"

Danny laughed merrily. "Don't worry," he

said, "I haven't gone crazy. I told you there was

something I was trying to remember. Well,

when we first stood up there on the top of the

cliff and looked down into this chamber. Pro-

fessor Bullfinch said there was a current of air

blowing through. But we had so many other

things to think about that we forgot it. Later,

when he lit his pipe and started blowing smoke

rings, they floated up perfectly a little way and

then dissolved. If we'd thought about it, then,

we'd have seen where the breeze was coming

from."

"Of course!" said Dr. Tresselt.

"And then Joe sneezed," Danny continued.

129

"Look at him. His eyes are watering and his

nose is all red. Irene, you know what that

means."

"His allergy 1" said Irene. "He's allergic to

goldenrod."

"But there's no goldenrod down here," the

Professor objected.

"No, but there's lots of it on Rose Hill, and

the far side of Sugarloaf is covered with it," said

Danny. "Do you know what I think? I think

we've traveled right through Sugarloaf, under

the ground, and now we're near the surface on

the side facing Rose Hill. The air is blowing in

here from some hole leading to the outside, and

it's carrying goldenrod pollen. It can't be too

far from the outside, or I'd guess there wouldn't

be enough pollen to start Joe's allergy working.

Right?"

"By George, I believe the boy has something,"

said Dr. Tresselt.

"He has the makings of a scientist," said Pro-

fessor Bullfinch, proudly. "Hold on, now, while

I light my pipe. Then we can trace the course

of the air current by watching the smoke."

In a short time, he had his pipe going. Dr.

Tresselt focused the beam of one of the battery

lamps on the plume of blue smoke. Deliber-

ately, the Professor puffed away and sent three

130

round, fat smoke rings floating lazily above his

head. They wavered, and shredded away.

"That way!" Danny pointed to the wall of

the cave opposite the side down which they had

climbed. "Dr. Tresselt, you help the Professor.

Professor, keep blowing smoke and walk toward

that wall. Come on, Joe and Irene, bring the

other lights and let's see what we can find."

The wall at which he had pointed rose in

a gradual slope above their heads. At the bot-

tom, it consisted of boulders and large chunks

of broken stone. But when they had climbed

over these, Danny, standing on a flat outcrop,

gave a yell.

"There's earth here I" he cried. "In among

the stones, there's plain old dirt."

Irene clambered a little higher and flashed

her light at the Professor's smoke cloud. "I

think the air is blowing from up here," she said.

"Yes—I can feel it on my face. Warm air, a

steady stream of it."

Danny joined her, and together they crawled

up still further until they were near the rocky

roof of the cave.

"Turn off your light," Danny said to Irene.

And when she had done so, he tapped her arm

and said, "Now look over there, to your left,

where that big chunk of rock is."

131

She blinked. A faint pencil of yellow light

shone through a crack in the earth.

"It's sunlight," said Danny, with satisfaction.

He scrambled over to the crack and began to

dig recklessly, throwing out the dirt with both

hands like a puppy.

"Watch outl" squealed Irene. "You're show-

ering mel"

He stopped, but already he had made a hole

as big as his head. The others, down below,

could see the golden daylight come streaming in.

"This is all loose dirt," Danny said. "It seems

to be held in place by a few big slabs of stone.

If Joe comes up here and helps me, we can really

excavate."

In a very short time, the two boys had grubbed

away an opening large enough for Danny to

squeeze through. He went out, headfirst. Aninstant later, he grinned down at them and

waved.

"I've got a pointed stick," he said. "Watch

out, Joe. Now you're going to see the dirt fly."

He attacked the edges of the hole, and with

Joe helping as best he could from the inside, they

soon made it large enough so that the men could

get out.

"Professor Bullfinch," Danny called. "Do

132

you think you can crawl up the slope with the

rope to help you?"

"My trousers may suffer," the Professor an-

swered, "but I think I can manage."

Irene brought the rope up and climbed out

of the hole. She and Danny held it fast, while

Dr. Tresselt and Joe helped the Professor up

over the rocks at the bottom. Then, holding

the rope to steady himself, the Professor slowly

and laboriously made his way up to the edge of

the hole, and so out into the sunlight.

The others followed, bringing the C-ray and

the knapsacks. They stood on the hillside,

blinking, and Joe spoke for all of them when

he said, "It feels as if we'd been let out of school

half a day early I"

They had emerged on a shoulder of the moun-

tain just above a long, narrow valley which

separated it from Rose Hill, which was some-

what lower and more rounded than Sugarloaf.

They sat down to catch their breaths, and to bask

for a while in the warmth of the sun after their

hours in the cool, dank darkness.

133

CHAPTER EIGHTEEN

Radioactive Danny

Danny said, "I'm just wondering—can't we go

back later and try to dig out the skeleton of the

dinosaur?"

Dr. Tresselt chuckled. "I'm afraid that job's

a little beyond our skill, Dan. Dinosaur fossils

are easily broken, and in the case of a good one,

such as this seems to be, it will take a whole gang

of men to get it out properly. I'll have to notify

my friend Dr. Purdy, at the Natural History

Museum."

"What will he do?"

"Well, he'll bring down a crew and first they'll

cut away all the rock above the skeleton so that

they can get down to it. Then, they'll start

chiseling out the rock around it, painting the

bones as they expose them with shellac to pre-

serve them. With a specimen of this size they

will probably then cut it up into blocks so that

they can handle it easily. Each block will be

coated with burlap covered with plaster, and

marked for identification. When the plaster is

134

hard, the blocks will be shipped off to the mu-

seum, where the staff will go to work on them.

They'll spend weeks cleaning, preparing, and

studying the fossil."

He looked about him. "Are you sure you

can find this place again, Dan?"

"Oh, yes. But to be on the safe side, I'll mark

it." Danny took up the long, pointed stick

which he had used for digging, and thrust it into

the ground a little way above the hole.

"Good. I should think that the museumwould be very grateful to you youngsters," said

Dr. Tresselt. "It isn't every day a fine specimen

like this comes along, and you all helped find it.

You'll be able to feel rather proud of yourselves,

when you see your names on the card the mu-

seum displays with this dinosaur."

"The thing I don't understand," said Danny,

"is how the dinosaur got down there and was

buried inside the rock. Do you think there was

an earthquake, and the tri—tricycle—whatever

it was—was caught in it?"

"TriceratopSj' said Dr. Tresselt. "The name

means 'three-horned face.' It had three horns,

one above each eye and the third on the beak,

something like the horn of a rhinoceros. Tri-

ceratops was a plant-eating dinosaur. It lived

at about the same time as Tyrannosaurus, the

135

'tyrant lizard,' a huge meat-eater which ran on

two legs, had a mouth full of teeth as long as

your arm, weighed six or seven tons, and could

look over the roof of your house. In spite of all

this, it had a hard time making its dinner off

Triceratops because the plant-eater's neck was

protected by a large fan, or collar, of bone, and

the three horns and sharp beak made it a hard

nut to crack.

"Your question about how it was buried is a

good one. I don't know the answer, of course,

but I can make a guess which may be something

like what really happened."

He stood up, shading his eyes, and waved his

arm. "Perhaps Professor Bullfinch has told you

that we believe this whole region was once cov-

ered by a sea," he said. "These limestone hills

are made of sediment—minerals, shells—that

settled slowly to the bottom of that sea in the

course of millions of years. Then the sea dried

up, or drew away, and the earth changed. Where

the sea had been, there were rivers which washed

dirt and mud and clay down into the valleys.

"This valley, between these hills, may once

have held such a river. For many reasons, it,

too, began to dry up and grow shallow. Perhaps

there were marshes here, with a muddy bottom.

136

"One day, Triceratops may have been brows-

ing in the reeds or grasses. Perhaps the big ty-

rant lizard chased him; perhaps he stumbled

into quicksand and couldn't escape. He sank

down into the mud—he was very heavy, after

all—and was buried.

"And more centuries passed, thousands of

years, millions—more than a hundred million

years. Imagine it! In all that time, the ground

sank and rose many times, very slowly, and the

mud turned to stone, and the skeleton of Tricera-

tops, snugly encased in it, turned to a kind of

stone as well. That petrified mud was the wall

of the cave down below, not limestone at all,

but the ancient marsh. There the fossil lay,

waiting for us to find it, an animal that lived

and died long before even the first tiny ancestor

of man appeared on the earth."

He fell silent, and the young people sat with

their chins on their knees, trying to imagine that

distant past.

Professor Bullfinch nodded, and said, "Help

me up, Alvin. I think it's time we went home.

Mrs. Dunn will be wondering what has become

of us."

They put on their packs and Danny found

another stick to serve as a cane for the Professor.

137

Irene, looking back at the hole through which

they had crawled, said, "There's one thing. . .

.

When they get through cutting away the rock

around that Triceratops, we'll have a new, big

entrance to the caves. People will be able to

explore them, to go right through the moun-

tain."

Joe covered his eyes with his hands. "I can

see it in my mind," he said. "Guided tours

—

electric lights—souvenirs—me with a beautiful

guide's uniform leading the people around

—

No! Wait a minute, change that. I'll be sitting

out here taking tickets, and you kids can be lead-

ing the people around."

"Leading people—!" Danny snapped his

fingers. "Nothing doing. We've got to keep

everybody away for a while."

"What do you mean, Dan? Why?" asked

Irene. "It isn't that dangerous. Anyway, we

can put a bridge over that gap, and mark the

passageways, and—

"

"I wasn't thinking of danger," Danny replied.

"I was thinking of our making a fortune from

our mine."

They all gaped at him with their mouths open.

"Our mine? What mine?" said the Professor,

at last.

138

"Our uranium mine! My gosh, have you all

forgotten how we were stuck in the glittering

cavern? How the Geiger counter blipped wher-

ever I turned it? The place must be loaded with

radioactive ore. I'll bet this whole hillside is

radioactive."

He slipped off his pack and quickly took out

the Geiger counter. "Just wait a sec," he said.

"It won't take long. Let me make a check on it."

He put on the earphones and pressed the

switch, turning the counter toward the ground.

"It is!" he exclaimed. "It's clicking like any-

thing!"

He began to scout about, first up the hill slope,

then down. His eyes were dancing, and his face

was split by an immense grin. "It's all radioac-

tive, wherever I turn the thing," he said. "We'll

be rich. We'll have the biggest mine in Amer-

ica.

The Professor had been watching him with

puckered brows. He said, "Danny, I find this

difficult to believe. The whole hillside—?"

"Try it for yourself," Danny said. He took

off the earphones and handed the instrument

to the Professor. Professor Bullfinch slipped

the phones on and pressed the switch. They

watched him eagerly.

139

"It's all radioactive."

"Nothing," he said.

"Nothing?" Danny goggled at him. "But

—

but I heard it—

"

"You try it, Alvin." The Professor handed

the Geiger counter to the geologist.

Dr. Tresselt began moving about slowly,

pointing the counter this way and that a little

distance above the surface of the earth. "Not

a sound," he said. "Very curious. Unless—

"

"Unless what?" asked the Professor.

"Unless Danny is radioactive."

With that, he turned the counter toward

Danny's feet.

"Ahal" he cried. "Listen to this." He held

up the earphones, and they could all hear the

faint ticks.

Danny turned pale. Then, his face grew very

red. Without a word, he bent down and turned

the cuff of his trouser leg inside out. Some small

white crystals, well mixed with fluff and dust,

fell out.

The Professor raised his eyebrows. "Thor-

ium nitrate?"

Danny nodded sheepishly. "When I dropped

it to mark the place where the passageway di-

vided, some must have fallen into the cuff of mypants."

He smiled ruefully at his friends. "Well,

there goes a fortune," he said.

Dr. Tresselt's brown, seamed face wrinkled

with amusement. "I think," he said, "that we've

already found something even better than a for-

tune. Everything that science can find out about

this earth we live on is valuable and important.

The caves, the fossil of Triceratops, will help us

learn a bit more about the history of our planet,

142

will tell us a few more of its secrets, and perhaps

even help us to make some good guesses about

its future."

"I know," said Danny, smiling up into the

faces of the two scientists.

"Sure, I agree," said Joe. "But golly, you

can't buy ice-cream sodas with just knowledge."

"Oh, if that's the problem, I think we can

solve it easily," said Professor Bullfinch. "Just

help me limp down to the house and get settled

comfortably, and then I think you can make the

soda fountain with ample time to spare before

dinner."

He took up his stick and put his free hand on

Dan's shoulder, for support. Then, slowly, but

joyfully, the Bullfinch-Tresselt Underground

Expedition marched down the hill to Midston

and its reward.

143

Authors' Note

Much of the cave material described in this book

is drawn from actual exploration of caves, made

over a number of years with my son, Christo-

pher, a member of the National Speleological

Society. For readers who would like to try un-

derground adventures for themselves, a list of

some caves open to the public follows. These

are all safe to enter and have guided tours, but

it should be remembered that caving can be ex-

tremely dangerous, and that no beginner should

try exploring new or unknown caves without

plenty of experienced supervision.

Crystal Caverns, Trussville, Alabama

Colossal Cave, Vail, Arizona

Diamond Caverns, Jasper, Arkansas

Boyden Cave, Sequoia National Forest, California

Cave of the Winds, Manitou Springs, Colorado

Florida Caverns, Florida Caverns State Park, near

Marianna, Florida

Cave Springs Cave, Cedartown, Georgia

Craters of the Moon Caves, near Arco, Idaho

144

Burksville Cave, Burksville, Illinois

Donaldson Cave, Spring Mill State Park, Mitchell,

Indiana

Crystal Lake Cave, near Dubuque, Iowa

Mammoth Cave, Mammoth Cave National Park,

Kentucky

Anemone Cave, Acadia National Park, Bar Harbor,

Maine

Crystal Grottoes, Boonsboro, Maryland

Mystery Cave, Spring Valley, Minnesota

Bridal Cave, Camdenton, Missouri

Lewis and Clark Cavern, Lewis and Clark Cavern State

Park, Whitehall, Montana

Lehman Caves, Baker, Nevada

Lost River Caverns, North Woodstock, New Hamp-

shire

Carlsbad Caverns, Carlsbad Caverns National Park,

Carlsbad, New Mexico

Howe Caverns, Cobleskill, New York

Linville Caverns, Ashford, North Carolina

Seneca Caverns, Bellevue, Ohio

Alabaster Caverns, Freedom, Oklahoma

Oregon Caves National Monument, Crater Lake

National Park, Oregon

Indian Caverns, Spruce Creek, Pennsylvania

Jewel Cave, Wind Cave National Park, Hot Springs,

South Dakota

Bristol Caverns, Bristol, Tennessee

Cascade Caverns, Boerne, Texas

Timpanogos Cave, American Fork, Utah

Luray Caverns, Luray, Virginia

Organ Cave, Ronceverte, West Virginia

145

Chelan Ice Caves, Lake Chelan State Park, Chelan,

Washington

Crystal Cave, Spring Valley, Wisconsin

This list was drawn from Exploring American

Caves, by Franklin Folsom, Crown Publishers,

Inc., New York, 1956, which not only contains

a much more complete and detailed list of caves,

but also much exciting information on cave ex-

ploration.

146

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